diff --git a/project/backend/api/tests.py b/project/backend/api/tests.py
index 51ce9f4e..a1e61861 100644
--- a/project/backend/api/tests.py
+++ b/project/backend/api/tests.py
@@ -563,4 +563,5 @@ def test_update_review_request(self):
         url = reverse('update_req')
         response = self.client.put(url, {'id': self.request.id, 'status': 'R'}, format='json')
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data['status'], 'R')
\ No newline at end of file
+        self.assertEqual(response.data['status'], 'R')
+
diff --git a/project/backend/api/wikidata.py b/project/backend/api/wikidata.py
new file mode 100644
index 00000000..fc4cd373
--- /dev/null
+++ b/project/backend/api/wikidata.py
@@ -0,0 +1,113 @@
+import requests
+import json
+
+def search_entity(keyword):
+    url = "https://www.wikidata.org/w/api.php"
+    params = {
+        "action" : "wbsearchentities",
+        "language" : "en",
+        "format" : "json",
+        "search" : keyword 
+    }
+
+    response = requests.get(url,params=params)
+    my_json = response.content.decode('utf8').replace("'", '"')
+    dic = json.loads(my_json)
+
+    results = []
+    for item in dic.get("search"):
+        block = {
+            "id": item.get("id"),
+            "label": item.get("display").get("label").get("value"),
+            "description": item.get("display").get("description").get("value")
+        }
+
+        results.append(block)
+
+    return results
+
+def get_parent_ids(entity_id):
+    url = "https://query.wikidata.org/sparql"
+
+    query = """
+        SELECT DISTINCT ?itemId
+        WHERE {
+            {
+                wd:""" + entity_id + """ wdt:P31 ?instanceOfEntity.
+            } UNION {
+                wd:""" + entity_id + """ wdt:P279 ?instanceOfEntity.
+            }
+            BIND(wikibase:decodeUri(REPLACE(STR(?instanceOfEntity), ".*Q", "Q")) AS ?itemId)
+            SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
+        }
+        """
+
+    params = {
+        "format" : "json",
+        "query" : query 
+        }
+    
+    response = requests.get(url, params=params)
+    my_json = response.content.decode('utf8').replace("'", '"')
+    dic = json.loads(my_json)
+
+    idlist = []
+
+    for item in dic.get("results").get("bindings"):
+        idlist.append(item.get("itemId").get("value"))
+
+    return idlist
+
+def get_children_ids(entity_id_list):
+    url = "https://query.wikidata.org/sparql"
+
+    head = """
+        SELECT DISTINCT ?itemId
+        WHERE {
+    """
+
+    body = """
+        {
+            ?item wdt:P31 wd:""" + entity_id_list[0] + """
+        }
+        UNION
+        {
+            ?item wdt:P279 wd:""" + entity_id_list[0] + """
+        }
+    """
+
+    for id in entity_id_list[1 : -1]:
+        block = """
+            UNION
+            {
+                ?item wdt:P31 wd:""" + id + """
+            }
+            UNION
+            {
+                ?item wdt:P279 wd:""" + id + """
+            }
+        """
+
+    tail = """
+            BIND(wikibase:decodeUri(REPLACE(STR(?item), ".*Q", "Q")) AS ?itemId)
+            SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
+        }
+    """
+
+    query = head + body + tail
+
+    params = {
+        "format" : "json",
+        "query" : query 
+        }
+    
+    response = requests.get(url, params=params)
+    my_json = response.content.decode('utf8').replace("'", '"')
+    dic = json.loads(my_json)
+
+    idlist = []
+
+    for item in dic.get("results").get("bindings"):
+        idlist.append(item.get("itemId").get("value"))
+
+    return idlist
diff --git a/project/backend/database/admin.py b/project/backend/database/admin.py
index 07facd1f..11256b46 100644
--- a/project/backend/database/admin.py
+++ b/project/backend/database/admin.py
@@ -13,7 +13,6 @@
 admin.site.register(Node)
 admin.site.register(Proof)
 admin.site.register(Question)
-admin.site.register(WikiTag)
 admin.site.register(Annotation)
 admin.site.register(Request)
 admin.site.register(ReviewRequest)
diff --git a/project/backend/database/models.py b/project/backend/database/models.py
index aa8d8bd8..0743d0d1 100644
--- a/project/backend/database/models.py
+++ b/project/backend/database/models.py
@@ -4,50 +4,55 @@
 import copy
 from datetime import datetime
 import enum
+from api.wikidata import *
 
 
 class SemanticTag(models.Model):
     created_at = models.DateTimeField(auto_now_add=True)
-    label = models.CharField(max_length=50, unique=True)
-    desc = models.CharField(max_length=100)
-    parent_tag = models.ForeignKey("SemanticTag", on_delete=models.CASCADE, null=True, blank=True,
-                                   related_name="sub_tags")
+    wid = models.CharField(max_length=20)
+    label = models.CharField(max_length=30, unique=True)
+    
+    @property
+    def nodes(self):
+        return Node.objects.filter(semantic_tags__wid=self.wid)
 
     @property
     def count(self):
-        return self.node_set.all().count()
-
+        return self.nodes.count()
+    
     @property
-    def nodes(self):
-        return self.node_set.all()
+    def related_nodes(self):
+        parent_wids = get_parent_ids(self.wid)
+        sibling_wids = get_children_ids(parent_wids)
 
-    @property
-    def recursive_nodes(self):
-        nodes = list(self.nodes)
+        if self.wid in sibling_wids:
+            sibling_wids.remove(self.wid)
 
-        for sub in self.sub_tags.all():
-            nodes.extend(sub.recursive_nodes)
+        children_wids = get_children_ids([self.wid])
+        combined = sibling_wids + parent_wids + children_wids
 
-        return nodes
+        return Node.objects.filter(semantic_tags__wid__in=combined)
 
     @property
-    def recursive_count(self):
-        return len(self.recursive_nodes)
+    def related_count(self):
+        return self.related_nodes.count()
+    
+    @classmethod
+    def existing_search_results(cls, keyword):
+        wiki_results = search_entity(keyword)
 
-    class Meta:
-        constraints = [
-            models.UniqueConstraint(fields=['label', 'parent_tag'],
-                                    name='semantictag_label_parenttag_unique_constraint')
-        ]
+        existings = []
+
+        for item in wiki_results:
+            node_count = Node.objects.filter(semantic_tags__wid=item["id"]).count()
+            if node_count > 0:
+                existings.append(item)
+
+        return existings
+    
+    def __str__(self):
+        return self.label + " - " + self.wid
 
-class WikiTag(models.Model):
-    pass
-class Request(models.Model):
-    """
-     This class definition is written beforehand (to be implemented afterwards)
-     in order to be referred from other classes. e.g. ReviewRequest
-    """
-    pass
 class Entry(models.Model):
     entry_id = models.AutoField(primary_key=True)
     entry_index = models.IntegerField()
@@ -200,7 +205,6 @@ class Node(models.Model):
     # Nodes also have to_referenced_nodes list to access the nodes this node references
     # Nodes also have a 'proofs' list which can be accessed as Node.proofs.all()
     semantic_tags = models.ManyToManyField(SemanticTag)
-    wiki_tags = models.ManyToManyField(WikiTag)
     annotations = models.ManyToManyField(Annotation)
     is_valid = models.BooleanField()
     num_visits = models.IntegerField()
diff --git a/project/backend/database/serializers.py b/project/backend/database/serializers.py
index 3e55f32f..a882e220 100644
--- a/project/backend/database/serializers.py
+++ b/project/backend/database/serializers.py
@@ -170,7 +170,7 @@ class NodeSerializer(serializers.ModelSerializer):
   class Meta:
     model = Node
     fields = ['node_id', 'node_title', 'publish_date', 'is_valid', 'num_visits' , 'theorem', 'contributors',
-                   'reviewers', 'from_referenced_nodes' , 'to_referenced_nodes', 'proofs' , 'question_set', 'semantic_tags', 'wiki_tags', 'annotations']
+                   'reviewers', 'from_referenced_nodes' , 'to_referenced_nodes', 'proofs' , 'question_set', 'semantic_tags', 'annotations']
 
 class RequestSerializer(serializers.ModelSerializer):
   class Meta:
diff --git a/project/backend/database/tests.py b/project/backend/database/tests.py
index 02d0eca7..6ebc8bc0 100644
--- a/project/backend/database/tests.py
+++ b/project/backend/database/tests.py
@@ -613,3 +613,80 @@ def test_reviewer_serializer_fields(self):
         )
         self.assertEqual(set(serializer.data.keys()), expected_fields)
 
+
+class SemanticTagModelTestCase(TestCase):
+    def setUp(self):
+        self.algo_tag = SemanticTag.objects.create(
+            wid="Q8366",
+            label="Algorithm"
+        )
+        self.search_tag = SemanticTag.objects.create(
+            wid="Q755673",
+            label="Search algorithm"
+        )
+        self.sort_tag = SemanticTag.objects.create(
+            wid="Q181593",
+            label="Sorting Agorithm"
+        )
+        self.combinational_tag = SemanticTag.objects.create(
+            wid="Q41883552",
+            label="Combinational Algorithm"
+        )
+
+        self.algo_node = Node.objects.create( #parent
+            node_title="Algorithm Node",
+            publish_date="2023-01-01",
+            is_valid=True,
+            num_visits=0,
+        )
+        self.algo_node.semantic_tags.add(self.algo_tag)
+
+        self.search_node = Node.objects.create(
+            node_title="Search Algorithm Node",
+            publish_date="2023-01-01",
+            is_valid=True,
+            num_visits=0,
+        )
+        self.search_node.semantic_tags.add(self.search_tag)
+
+        self.sort_node = Node.objects.create(
+            node_title="Sorting algorithm Node",
+            publish_date="2023-01-01",
+            is_valid=True,
+            num_visits=0,
+        )
+        self.sort_node.semantic_tags.add(self.sort_tag)
+
+        self.combinational_node = Node.objects.create(
+            node_title="Combinational Algorithm Node",
+            publish_date="2023-01-01",
+            is_valid=True,
+            num_visits=0,
+        )
+        self.combinational_node.semantic_tags.add(self.combinational_tag)
+
+    def tearDown(self):
+        Node.objects.all().delete()
+        SemanticTag.objects.all().delete()
+        print("All tests for the Semantic Tag Model are completed!")
+
+    def test_search(self):
+        search_res = SemanticTag.existing_search_results("sorting algorithm")
+        l = len(search_res)
+        self.assertEqual(1, l, "Search result length is wrong!")
+
+        if l:
+            self.assertEqual(self.sort_tag.wid, search_res[0]["id"], "Search result id mismatch!")
+
+    def test_nodes(self):
+        self.assertEqual(self.sort_tag.count, 1, "Sort tag node count mismatch!")
+        if self.sort_tag.count:
+            self.assertEqual(self.sort_tag.nodes[0].pk, self.sort_node.pk, "Sort nodes mismatch!")
+
+        self.assertEqual(self.combinational_tag.related_count, 3, "Combinational tag related count mismatch!")
+        if self.combinational_tag.related_count:
+            r_nodes = self.combinational_tag.related_nodes
+            self.assertIn(self.algo_node, r_nodes, "Algorithm node not in related nodes of combintaional semantic tag!")
+            self.assertIn(self.search_node, r_nodes, "Search node not in related nodes of combintaional semantic tag!")
+            self.assertIn(self.sort_node, r_nodes, "Sort node not in related nodes of combintaional semantic tag!")
+
diff --git a/project/backend/requirements.txt b/project/backend/requirements.txt
index 9a11b6d1..c7fa7980 100644
--- a/project/backend/requirements.txt
+++ b/project/backend/requirements.txt
@@ -2,4 +2,5 @@ Django==4.2.6
 djangorestframework==3.14.0
 psycopg==3.1.12
 psycopg-binary==3.1.12
-django-cors-headers==4.3.0
\ No newline at end of file
+django-cors-headers==4.3.0
+requests