diff --git a/src/core/embedder.py b/src/core/embedder.py
index a11fada..ff35556 100644
--- a/src/core/embedder.py
+++ b/src/core/embedder.py
@@ -18,6 +18,7 @@
     vectors = batch_embed(embedder, long_text_list)
 """
 import os
+import threading
 import logging
 from typing import Protocol
 
@@ -29,6 +30,8 @@ logger = logging.getLogger("md-vector-db")
 
 _HF_MIRROR = os.environ.get("HF_MIRROR", "https://hf-mirror.com")
 
+_HF_ENV_LOCK = threading.Lock()
+
 # -- Provider 默认配置 --
 _PROVIDER_DEFAULTS: dict[str, dict[str, str | int]] = {
     "openai": {
@@ -78,16 +81,18 @@ class LocalEmbedder:
             # 通过 HF_ENDPOINT 环境变量设置镜像（sentence-transformers 依赖 huggingface_hub）
             # 临时设置仅用于模型下载，下载完成后还原
             old_endpoint = os.environ.get("HF_ENDPOINT")
-            os.environ["HF_ENDPOINT"] = _HF_MIRROR
+            with _HF_ENV_LOCK:
+                os.environ["HF_ENDPOINT"] = _HF_MIRROR
             try:
                 self._model = SentenceTransformer(
                     config.local_model, device=device
                 )
             finally:
-                if old_endpoint is not None:
-                    os.environ["HF_ENDPOINT"] = old_endpoint
-                else:
-                    os.environ.pop("HF_ENDPOINT", None)
+                with _HF_ENV_LOCK:
+                    if old_endpoint is not None:
+                        os.environ["HF_ENDPOINT"] = old_endpoint
+                    else:
+                        os.environ.pop("HF_ENDPOINT", None)
 
     @property
     def dimension(self) -> int: