diff --git a/lib/lor/lib/application.lua b/lib/lor/lib/application.lua
index 25ad427..8611153 100755
--- a/lib/lor/lib/application.lua
+++ b/lib/lor/lib/application.lua
@@ -82,7 +82,7 @@ function App:handle(req, res, callback)
     local done = callback or function(err)
         if err then
             if ngx then ngx.log(ngx.ERR, err) end
-            res:status(500):send("unknown error.")
+            res:status(500):send("internal error! please check log.")
         end
     end
 
diff --git a/lib/lor/lib/router/group.lua b/lib/lor/lib/router/group.lua
index 6bc109d..61a2019 100644
--- a/lib/lor/lib/router/group.lua
+++ b/lib/lor/lib/router/group.lua
@@ -1,14 +1,19 @@
 local setmetatable = setmetatable
 local pairs = pairs
 local type = type
+local error = error
+local next = next
 local string_format = string.format
 local string_lower = string.lower
+local table_insert = table.insert
+local unpack = table.unpack or unpack
 
 local supported_http_methods = require("lor.lib.methods")
 local debug = require("lor.lib.debug")
 local utils = require("lor.lib.utils.utils")
 local random = utils.random
 local clone = utils.clone
+local handler_error_tip = "handler must be `function` that matches `function(req, res, next) ... end`"
 
 local Group = {}
 
@@ -45,29 +50,83 @@ function Group:get_apis()
     return self.apis
 end
 
-function Group:set_api(path, method, func)
-    if not path or not method or not func then
-        return error("params should not be nil.")
+function Group:set_api(path, method, ...)
+    if not path or not method then
+        return error("`path` & `method` should not be nil.")
     end
 
-    if type(path) ~= "string" or type(method) ~= "string" or type(func) ~= "function" then
+    local handlers = {...}
+    if not next(handlers) then
+        return error("handler should not be nil or empty")
+    end
+
+    if type(path) ~= "string" or type(method) ~= "string" or type(handlers) ~= "table" then
         return error("params type error.")
     end
 
+    local extended_handlers = {}
+    for _, h in ipairs(handlers) do
+        if type(h) == "function" then
+            table_insert(extended_handlers, h)
+        elseif type(h) == "table" then
+            for _, hh in ipairs(h) do
+                if type(hh) == "function" then
+                    table_insert(extended_handlers, hh)
+                else
+                    error(handler_error_tip)
+                end
+            end
+        else
+            error(handler_error_tip)
+        end
+    end
+
     method = string_lower(method)
     if not supported_http_methods[method] then
         return error(string_format("[%s] method is not supported yet.", method))
     end
 
     self.apis[path] = self.apis[path] or {}
-    self.apis[path][method] = func
+    self.apis[path][method] = extended_handlers
 end
 
 function Group:build_method()
     for m, _ in pairs(supported_http_methods) do
         m = string_lower(m)
-        Group[m] = function(myself, path, func)
-            Group.set_api(myself, path, m, func)
+
+        -- 1. group_router:get(func1)
+        -- 2. group_router:get(func1, func2)
+        -- 3. group_router:get({func1, func2})
+        -- 4. group_router:get(path, func1)
+        -- 5. group_router:get(path, func1, func2)
+        -- 6. group_router:get(path, {func1, func2})
+        Group[m] = function(myself, ...)
+            local params = {...}
+            if not next(params) then return error("params should not be nil or empty") end
+
+            -- case 1 or 3
+            if #params == 1 then
+                if type(params[1]) ~= "function" and type(params[1]) ~= "table" then
+                    return error("it must be an function if there's only one param")
+                end
+
+                if type(params[1]) == "table" and #(params[1]) == 0 then
+                    return error("params should not be nil or empty")
+                end
+
+                return Group.set_api(myself, "", m, ...)
+            end
+
+            -- case 2,4,5,6
+            if #params > 1 then
+                if type(params[1]) == "string" then -- case 4,5,6
+                    return Group.set_api(myself, params[1], m, unpack(params, 2))
+                else -- case 2
+                    return Group.set_api(myself, "", m, ...)
+                end
+            end
+
+            error("error params for group route define")
         end
     end
 end
diff --git a/lib/lor/lib/router/router.lua b/lib/lor/lib/router/router.lua
index dfe7f65..65f7778 100755
--- a/lib/lor/lib/router/router.lua
+++ b/lib/lor/lib/router/router.lua
@@ -3,6 +3,7 @@ local ipairs = ipairs
 local pcall = pcall
 local xpcall = xpcall
 local type = type
+local error = error
 local setmetatable = setmetatable
 local traceback = debug.traceback
 local tinsert = table.insert
@@ -287,21 +288,27 @@ function Router:merge_group(prefix, group)
     if apis then
         for uri, api_methods in pairs(apis) do
             if type(api_methods) == "table" then
-                local path = utils.clear_slash(prefix .. "/" .. uri)
+                local path
+                if uri == "" then -- for group index route
+                    path = utils.clear_slash(prefix)
+                else
+                    path = utils.clear_slash(prefix .. "/" .. uri)
+                end
+
                 local node = self.trie:add_node(path)
                 if not node then
                     return error("cann't define node on router trie, path:" .. path)
                 end
 
-                for method, func in pairs(api_methods) do
+                for method, handlers in pairs(api_methods) do
                     local m = string_lower(method)
                     if supported_http_methods[m] == true then
-                        node:handle(m, func)
-                    end
+                        node:handle(m, handlers)
+                    end -- supported method
                 end
             end
         end
-    end
+    end -- ugly arrow style for missing `continue`
 
     return self
 end
diff --git a/spec/cases/group_index_route_spec.lua b/spec/cases/group_index_route_spec.lua
new file mode 100644
index 0000000..dc657ef
--- /dev/null
+++ b/spec/cases/group_index_route_spec.lua
@@ -0,0 +1,165 @@
+before_each(function()
+    lor = _G.lor
+    app = lor({
+        debug = true
+    })
+    Request = _G.request
+    Response = _G.response
+    req = Request:new()
+    res = Response:new()
+end)
+
+after_each(function()
+    lor = nil
+    app = nil
+    Request = nil
+    Response = nil
+    req = nil
+    res = nil
+end)
+
+
+describe("group index route: basic usages", function()
+    it("should be error when giving wrong params", function()
+        local flag = 0
+        local test_router = lor:Router()
+
+        assert.has_error(function() test_router:get() end, "params should not be nil or empty")
+        assert.has_error(function() test_router:get({}) end, "params should not be nil or empty")
+
+        assert.has_error(function() test_router:get("/test") end, "it must be an function if there's only one param")
+        assert.has_error(function() test_router:get("/test", "abc") end)
+    end)
+
+    it("uri should mathed", function()
+        local flag = 0
+
+        local test_router = lor:Router()
+        test_router:get(function(req, res, next)
+            flag = 1
+        end)
+
+        app:use("/test", test_router())
+
+        req.path = "/test"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(1, flag)
+    end)
+
+    it("uri should not mathed", function()
+        local flag = 0
+
+        local test_router = lor:Router()
+        test_router:get(function(req, res, next)
+            flag = 1
+        end)
+
+        app:use("/test", test_router())
+        app:erroruse(function(err, req, res, next) -- 404 error
+            assert.is.truthy(err)
+            assert.is.equals(false, req:is_found())
+            flag = 999
+        end)
+
+        req.path = "/test/"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(999, flag)
+    end)
+end)
+
+
+describe("group index route: multi funcs", function()
+    it("array params", function()
+        local flag = 0
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 3
+        end
+        test_router:post({func1, func2, last_func})
+        app:use("/test", test_router())
+
+        req.path = "/test"
+        req.method = "post"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+    end)
+
+    it("unpacked params", function()
+        local flag = 0
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 3
+        end
+        test_router:put(func1, func2, last_func)
+        app:use("/test", test_router())
+
+        req.path = "/test"
+        req.method = "put"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+    end)
+
+    it("mixed params, case1", function()
+        local flag = 0
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 3
+        end
+        test_router:get({func1, func2}, last_func)
+        app:use("/test", test_router())
+
+        req.path = "/test"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+    end)
+
+    it("mixed params, case2", function()
+        local flag = 0
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 3
+        end
+        test_router:put({func1}, func2, {last_func})
+        app:use("/test", test_router())
+
+        req.path = "/test"
+        req.method = "put"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+    end)
+end)
diff --git a/spec/cases/multi_route_spec.lua b/spec/cases/multi_route_spec.lua
new file mode 100644
index 0000000..b3b3b0f
--- /dev/null
+++ b/spec/cases/multi_route_spec.lua
@@ -0,0 +1,254 @@
+before_each(function()
+    lor = _G.lor
+    app = lor({
+        debug = true
+    })
+    Request = _G.request
+    Response = _G.response
+    req = Request:new()
+    res = Response:new()
+end)
+
+after_each(function()
+    lor = nil
+    app = nil
+    Request = nil
+    Response = nil
+    req = nil
+    res = nil
+end)
+
+
+describe("multi route: mounted on `app`", function()
+    it("array param", function()
+        local flag = 0
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = req.query.flag or 3
+        end
+        app:get("/flag", {func1, func2, last_func})
+
+        app:erroruse(function(err, req, res, next)
+            assert.is.truthy(err) -- should not reach here.
+            flag = 999
+        end)
+
+        req.path = "/flag"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+
+        req.path = "/flag"
+        req.query = {flag=111}
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(111, flag)
+    end)
+
+    it("unpacked params", function()
+        local flag = 0
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = req.query.flag or 3
+        end
+        app:get("/flag", func1, func2, last_func)
+
+        app:erroruse(function(err, req, res, next)
+            assert.is.truthy(err) -- should not reach here.
+            flag = 999
+        end)
+
+        req.path = "/flag"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+
+        req.path = "/flag"
+        req.query = {flag=111}
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(111, flag)
+    end)
+end)
+
+describe("multi route: mounted on `group router`", function()
+    it("array param", function()
+        local flag = 0
+
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = req.query.flag or 3
+        end
+        test_router:get("/flag", {func1, func2, last_func})
+
+        app:use("/test", test_router())
+        app:erroruse(function(err, req, res, next)
+            assert.is.truthy(err) -- should not reach here.
+            flag = 999
+        end)
+
+        req.path = "/test/flag"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+
+        req.path = "/test/flag"
+        req.query = {flag=111}
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(111, flag)
+    end)
+
+    it("unpacked params", function()
+        local flag = 0
+
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = req.query.flag or 3
+        end
+        test_router:get("/flag", func1, func2, last_func)
+
+        app:use("/test", test_router())
+        app:erroruse(function(err, req, res, next)
+            assert.is.truthy(err) -- should not reach here.
+            flag = 999
+        end)
+
+        req.path = "/test/flag"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+
+        req.path = "/test/flag"
+        req.query = {flag=111}
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(111, flag)
+    end)
+end)
+
+describe("multi route: muixed funcs for group router", function()
+    it("mixed params, case1", function()
+        local flag = 0
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 3
+        end
+        test_router:put("mixed", {func1, func2}, last_func)
+        app:use("/test", test_router())
+
+        req.path = "/test/mixed"
+        req.method = "put"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+    end)
+
+    it("mixed params, case2", function()
+        local flag = 0
+        local test_router = lor:Router()
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 3
+        end
+        test_router:get("mixed", {func1}, func2, {last_func})
+        app:use("/test", test_router())
+
+        req.path = "/test/mixed"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+    end)
+end)
+
+describe("multi route: muixed funcs for `app`", function()
+    it("mixed params, case1", function()
+        local flag = 0
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 3
+        end
+        app:get("mixed", {func1, func2}, last_func)
+
+        req.path = "/mixed"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(3, flag)
+    end)
+
+    it("mixed params, case2", function()
+        local flag = 0
+        local func1 = function(req, res, next)
+            flag = 1
+            next()
+        end
+        local func2 = function(req, res, next)
+            flag = 2
+            next()
+        end
+        local func3 = function(req, res, next)
+            flag = 3
+            next()
+        end
+        local last_func = function(req, res, next)
+            flag = 4
+        end
+        app:get("mixed", {func1}, func2, {func3}, last_func)
+
+        req.path = "/mixed"
+        req.method = "get"
+        app:handle(req, res)
+        assert.is.equals(4, flag)
+    end)
+end)
diff --git a/spec/cases/path_pattern_2_spec.lua b/spec/cases/path_pattern_2_spec.lua
index 83241d9..e6514f7 100755
--- a/spec/cases/path_pattern_2_spec.lua
+++ b/spec/cases/path_pattern_2_spec.lua
@@ -59,6 +59,10 @@ describe("path match test", function()
     it("test case 3", function()
         req.path = "/test/find/all/1"
         req.method = "get"
+        app:erroruse(function(err, req, res, next) -- 404 error
+            assert.is.truthy(err)
+            assert.is.equals(false, req:is_found())
+        end)
         app:handle(req, res)
         assert.is.equals(1, match)
         assert.is.equals(0, count)