diff --git a/api/core/rag/datasource/vdb/chroma/chroma_vector.py b/api/core/rag/datasource/vdb/chroma/chroma_vector.py
index cbc846f7162..3e0420b9d03 100644
--- a/api/core/rag/datasource/vdb/chroma/chroma_vector.py
+++ b/api/core/rag/datasource/vdb/chroma/chroma_vector.py
@@ -6,7 +6,7 @@ from chromadb import QueryResult, Settings
 from pydantic import BaseModel
 
 from configs import dify_config
-from core.rag.datasource.vdb.vector_base import BaseVector
+from core.rag.datasource.vdb.vector_base import BaseVector, VectorIndexStructDict
 from core.rag.datasource.vdb.vector_factory import AbstractVectorFactory
 from core.rag.datasource.vdb.vector_type import VectorType
 from core.rag.embedding.embedding_base import Embeddings
@@ -145,7 +145,10 @@ class ChromaVectorFactory(AbstractVectorFactory):
         else:
             dataset_id = dataset.id
             collection_name = Dataset.gen_collection_name_by_id(dataset_id).lower()
-            index_struct_dict = {"type": VectorType.CHROMA, "vector_store": {"class_prefix": collection_name}}
+            index_struct_dict: VectorIndexStructDict = {
+                "type": VectorType.CHROMA,
+                "vector_store": {"class_prefix": collection_name},
+            }
             dataset.index_struct = json.dumps(index_struct_dict)
 
         return ChromaVector(
diff --git a/api/core/rag/datasource/vdb/vector_factory.py b/api/core/rag/datasource/vdb/vector_factory.py
index 26531eab886..0ef88e10106 100644
--- a/api/core/rag/datasource/vdb/vector_factory.py
+++ b/api/core/rag/datasource/vdb/vector_factory.py
@@ -9,7 +9,7 @@ from sqlalchemy import select
 
 from configs import dify_config
 from core.model_manager import ModelManager
-from core.rag.datasource.vdb.vector_base import BaseVector
+from core.rag.datasource.vdb.vector_base import BaseVector, VectorIndexStructDict
 from core.rag.datasource.vdb.vector_type import VectorType
 from core.rag.embedding.cached_embedding import CacheEmbedding
 from core.rag.embedding.embedding_base import Embeddings
@@ -30,8 +30,11 @@ class AbstractVectorFactory(ABC):
         raise NotImplementedError
 
     @staticmethod
-    def gen_index_struct_dict(vector_type: VectorType, collection_name: str):
-        index_struct_dict = {"type": vector_type, "vector_store": {"class_prefix": collection_name}}
+    def gen_index_struct_dict(vector_type: VectorType, collection_name: str) -> VectorIndexStructDict:
+        index_struct_dict: VectorIndexStructDict = {
+            "type": vector_type,
+            "vector_store": {"class_prefix": collection_name},
+        }
         return index_struct_dict