diff --git a/metagpt/exp_pool/manager.py b/metagpt/exp_pool/manager.py
index d6922ff00..9bf289038 100644
--- a/metagpt/exp_pool/manager.py
+++ b/metagpt/exp_pool/manager.py
@@ -1,7 +1,8 @@
 """Experience Manager."""
 
-from llama_index.vector_stores.chroma import ChromaVectorStore
-from pydantic import BaseModel, ConfigDict, model_validator
+from typing import TYPE_CHECKING, Any
+
+from pydantic import BaseModel, ConfigDict
 
 from metagpt.config2 import Config, config
 from metagpt.exp_pool.schema import (
@@ -11,27 +12,37 @@ from metagpt.exp_pool.schema import (
     QueryType,
 )
 from metagpt.logs import logger
-from metagpt.rag.engines import SimpleEngine
-from metagpt.rag.schema import ChromaRetrieverConfig, LLMRankerConfig
 from metagpt.utils.exceptions import handle_exception
 
+if TYPE_CHECKING:
+    from llama_index.vector_stores.chroma import ChromaVectorStore
+
 
 class ExperienceManager(BaseModel):
     """ExperienceManager manages the lifecycle of experiences, including CRUD and optimization.
 
     Args:
         config (Config): Configuration for managing experiences.
-        storage (SimpleEngine): Engine to handle the storage and retrieval of experiences.
+        _storage (SimpleEngine): Engine to handle the storage and retrieval of experiences.
+        _vector_store (ChromaVectorStore): The actual place where vectors are stored.
     """
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
     config: Config = config
-    storage: SimpleEngine = None
 
-    @model_validator(mode="after")
-    def initialize(self):
-        if self.storage is None:
+    _storage: Any = None
+    _vector_store: Any = None
+
+    @property
+    def storage(self):
+        if self._storage is None:
+            try:
+                from metagpt.rag.engines import SimpleEngine
+                from metagpt.rag.schema import ChromaRetrieverConfig, LLMRankerConfig
+            except ImportError:
+                raise ImportError("To use the experience pool, you need to install the rag module.")
+
             retriever_configs = [
                 ChromaRetrieverConfig(
                     persist_path=self.config.exp_pool.persist_path,
@@ -41,14 +52,19 @@ class ExperienceManager(BaseModel):
             ]
             ranker_configs = [LLMRankerConfig(top_n=DEFAULT_SIMILARITY_TOP_K)]
 
-            self.storage = SimpleEngine.from_objs(retriever_configs=retriever_configs, ranker_configs=ranker_configs)
+            self._storage: SimpleEngine = SimpleEngine.from_objs(
+                retriever_configs=retriever_configs, ranker_configs=ranker_configs
+            )
+            logger.debug(f"exp_pool config: {self.config.exp_pool}")
 
-        logger.debug(f"exp_pool config: {self.config.exp_pool}")
-        return self
+        return self._storage
 
     @property
-    def vector_store(self) -> ChromaVectorStore:
-        return self.storage._retriever._vector_store
+    def vector_store(self):
+        if not self._vector_store:
+            self._vector_store: ChromaVectorStore = self.storage._retriever._vector_store
+
+        return self._vector_store
 
     @handle_exception
     def create_exp(self, exp: Experience):