diff --git a/metagpt/rag/engines/simple.py b/metagpt/rag/engines/simple.py
index c237dcf69..03b645420 100644
--- a/metagpt/rag/engines/simple.py
+++ b/metagpt/rag/engines/simple.py
@@ -220,7 +220,9 @@ class SimpleEngine(RetrieverQueryEngine):
         embed_model = cls._resolve_embed_model(embed_model, retriever_configs)
         llm = llm or get_rag_llm()
 
-        retriever = get_retriever(configs=retriever_configs, nodes=nodes, embed_model=embed_model)
+        retriever = get_retriever(
+            configs=retriever_configs, nodes=nodes, embed_model=embed_model
+        )  # Default VectorStoreIndex(nodes, embed_model).as_retriever
         rankers = get_rankers(configs=ranker_configs, llm=llm)  # Default []
 
         return cls(
diff --git a/metagpt/rag/factories/retriever.py b/metagpt/rag/factories/retriever.py
index dd6261d52..a3b2268fd 100644
--- a/metagpt/rag/factories/retriever.py
+++ b/metagpt/rag/factories/retriever.py
@@ -1,6 +1,8 @@
 """RAG Retriever Factory."""
 
 
+from functools import wraps
+
 import chromadb
 import faiss
 from llama_index.core import StorageContext, VectorStoreIndex
@@ -28,6 +30,22 @@ from metagpt.rag.schema import (
 )
 
 
+def get_or_build_index(build_index_func):
+    """Find index using `_extract_index` method.
+
+    If no index is found, using build_index_func.
+    """
+
+    @wraps(build_index_func)
+    def wrapper(self, config, **kwargs):
+        index = self._extract_index(config, **kwargs)
+        if index is not None:
+            return index
+        return build_index_func(self, config, **kwargs)
+
+    return wrapper
+
+
 class RetrieverFactory(ConfigBasedFactory):
     """Modify creators for dynamically instance implementation."""
 
@@ -59,12 +77,13 @@ class RetrieverFactory(ConfigBasedFactory):
         return index.as_retriever()
 
     def _create_faiss_retriever(self, config: FAISSRetrieverConfig, **kwargs) -> FAISSRetriever:
-        config.index = self._extract_index(config, **kwargs) or self._build_faiss_index(config, **kwargs)
+        config.index = self._build_faiss_index(config, **kwargs)
 
         return FAISSRetriever(**config.model_dump())
 
     def _create_bm25_retriever(self, config: BM25RetrieverConfig, **kwargs) -> DynamicBM25Retriever:
-        nodes = self._extract_nodes(config, **kwargs)
+        index = self._extract_index(config, **kwargs)
+        nodes = list(index.docstore.docs.values()) if index else self._extract_nodes(config, **kwargs)
 
         return DynamicBM25Retriever(nodes=nodes, **config.model_dump())
 
@@ -95,11 +114,13 @@ class RetrieverFactory(ConfigBasedFactory):
 
         return index
 
+    @get_or_build_index
     def _build_faiss_index(self, config: FAISSRetrieverConfig, **kwargs) -> VectorStoreIndex:
         vector_store = FaissVectorStore(faiss_index=faiss.IndexFlatL2(config.dimensions))
 
         return self._build_index_from_vector_store(config, vector_store, **kwargs)
 
+    @get_or_build_index
     def _build_chroma_index(self, config: ChromaRetrieverConfig, **kwargs) -> VectorStoreIndex:
         db = chromadb.PersistentClient(path=str(config.persist_path))
         chroma_collection = db.get_or_create_collection(config.collection_name, metadata=config.metadata)
@@ -107,6 +128,7 @@ class RetrieverFactory(ConfigBasedFactory):
 
         return self._build_index_from_vector_store(config, vector_store, **kwargs)
 
+    @get_or_build_index
     def _build_es_index(self, config: ElasticsearchRetrieverConfig, **kwargs) -> VectorStoreIndex:
         vector_store = ElasticsearchStore(**config.store_config.model_dump())
 
diff --git a/tests/metagpt/rag/factories/test_retriever.py b/tests/metagpt/rag/factories/test_retriever.py
index a70639f55..cd55a32db 100644
--- a/tests/metagpt/rag/factories/test_retriever.py
+++ b/tests/metagpt/rag/factories/test_retriever.py
@@ -119,3 +119,19 @@ class TestRetrieverFactory:
         extracted_index = self.retriever_factory._extract_index(index=mock_vector_store_index)
 
         assert extracted_index == mock_vector_store_index
+
+    def test_get_or_build_when_get(self, mocker):
+        want = "existing_index"
+        mocker.patch.object(self.retriever_factory, "_extract_index", return_value=want)
+
+        got = self.retriever_factory._build_es_index(None)
+
+        assert got == want
+
+    def test_get_or_build_when_build(self, mocker):
+        want = "call_build_es_index"
+        mocker.patch.object(self.retriever_factory, "_build_es_index", return_value=want)
+
+        got = self.retriever_factory._build_es_index(None)
+
+        assert got == want