diff --git a/chains/local_doc_qa.py b/chains/local_doc_qa.py
index de1a9f6e..84f820c9 100644
--- a/chains/local_doc_qa.py
+++ b/chains/local_doc_qa.py
@@ -1,16 +1,13 @@
-from langchain.chains import RetrievalQA
-from langchain.prompts import PromptTemplate
 from langchain.embeddings.huggingface import HuggingFaceEmbeddings
 from langchain.vectorstores import FAISS
 from langchain.document_loaders import UnstructuredFileLoader
 from models.chatglm_llm import ChatGLM
-import sentence_transformers
-import os
 from configs.model_config import *
 import datetime
-from typing import List
 from textsplitter import ChineseTextSplitter
+from typing import List, Tuple
 from langchain.docstore.document import Document
+import numpy as np
 
 # return top-k text chunk from vector store
 VECTOR_SEARCH_TOP_K = 6
@@ -48,10 +45,70 @@ def get_docs_with_score(docs_with_score):
         docs.append(doc)
     return docs
 
+
+def seperate_list(ls: List[int]) -> List[List[int]]:
+    lists = []
+    ls1 = [ls[0]]
+    for i in range(1, len(ls)):
+        if ls[i-1] + 1 == ls[i]:
+            ls1.append(ls[i])
+        else:
+            lists.append(ls1)
+            ls1 = [ls[i]]
+    lists.append(ls1)
+    return lists
+
+
+
+def similarity_search_with_score_by_vector(
+        self,
+        embedding: List[float],
+        k: int = 4,
+    ) -> List[Tuple[Document, float]]:
+        scores, indices = self.index.search(np.array([embedding], dtype=np.float32), k)
+        docs = []
+        id_set = set()
+        for j, i in enumerate(indices[0]):
+            if i == -1:
+                # This happens when not enough docs are returned.
+                continue
+            _id = self.index_to_docstore_id[i]
+            doc = self.docstore.search(_id)
+            id_set.add(i)
+            docs_len = len(doc.page_content)
+            for k in range(1, max(i, len(docs)-i)):
+                for l in [i+k, i-k]:
+                    if 0 <= l < len(self.index_to_docstore_id):
+                        _id0 = self.index_to_docstore_id[l]
+                        doc0 = self.docstore.search(_id0)
+                        if docs_len + len(doc0.page_content) > self.chunk_size:
+                            break
+                        elif doc0.metadata["source"] == doc.metadata["source"]:
+                            docs_len += len(doc0.page_content)
+                            id_set.add(l)
+        id_list = sorted(list(id_set))
+        id_lists = seperate_list(id_list)
+        for id_seq in id_lists:
+            for id in id_seq:
+                if id == id_seq[0]:
+                    _id = self.index_to_docstore_id[id]
+                    doc = self.docstore.search(_id)
+                else:
+                    _id0 = self.index_to_docstore_id[id]
+                    doc0 = self.docstore.search(_id0)
+                    doc.page_content += doc0.page_content
+            if not isinstance(doc, Document):
+                raise ValueError(f"Could not find document for id {_id}, got {doc}")
+            docs.append((doc, scores[0][j]))
+        return docs
+
+
+
 class LocalDocQA:
     llm: object = None
     embeddings: object = None
     top_k: int = VECTOR_SEARCH_TOP_K
+    chunk_size: int = CHUNK_SIZE
 
     def init_cfg(self,
                  embedding_model: str = EMBEDDING_MODEL,
@@ -133,6 +190,8 @@ class LocalDocQA:
                                    streaming=True):
         self.llm.streaming = streaming
         vector_store = FAISS.load_local(vs_path, self.embeddings)
+        FAISS.similarity_search_with_score_by_vector = similarity_search_with_score_by_vector
+        vector_store.chunk_size=self.chunk_size
         related_docs_with_score = vector_store.similarity_search_with_score(query,
                                                                             k=self.top_k)
         related_docs = get_docs_with_score(related_docs_with_score)
diff --git a/configs/model_config.py b/configs/model_config.py
index b0093bc7..1afc5379 100644
--- a/configs/model_config.py
+++ b/configs/model_config.py
@@ -39,4 +39,7 @@ UPLOAD_ROOT_PATH = os.path.join(os.path.dirname(os.path.dirname(__file__)), "con
 
 # 基于上下文的prompt模版，请务必保留"{question}"和"{context}"
 PROMPT_TEMPLATE = """基于以下已知信息，简洁和专业的来回答用户的问题，问题是"{question}"。如果无法从中得到答案，请说 "根据已知信息无法回答该问题" 或 "没有提供足够的相关信息"，不允许在答案中添加编造成分，答案请使用中文。已知内容如下: 
-{context} """
\ No newline at end of file
+{context} """
+
+# 匹配后单段上下文长度
+CHUNK_SIZE = 500
\ No newline at end of file