diff --git a/ruoyi-fastapi-backend/.env.dev b/ruoyi-fastapi-backend/.env.dev
index ee1d3b6..fbbe8c7 100644
--- a/ruoyi-fastapi-backend/.env.dev
+++ b/ruoyi-fastapi-backend/.env.dev
@@ -154,7 +154,7 @@ SEARCH_CACHE_TTL = 1800
 #-------------------KB ES/BM25（测试环境）-------------------
 KB_PROVIDER=es_bm25
 KB_ES_URL=http://127.0.0.1:1200
-KB_ES_INDEX=kb_chunks_v1
+KB_ES_INDEX=kb_qa_v1
 KB_ES_USERNAME=elastic
 KB_ES_PASSWORD=infini_rag_flow
 KB_ES_VERIFY_SSL=true
diff --git a/ruoyi-fastapi-backend/config/env.py b/ruoyi-fastapi-backend/config/env.py
index 6060652..285e721 100644
--- a/ruoyi-fastapi-backend/config/env.py
+++ b/ruoyi-fastapi-backend/config/env.py
@@ -239,26 +239,41 @@ class DeepSeekSettings:
     DEEPSEEK_MODEL = os.getenv("DEEPSEEK_MODEL", "deepseek-chat")
 
 
-class KBSettings:
-    """内部知识库 Provider 配置（ragflow / es_bm25）"""
+class KBSettings(BaseSettings):
+    """内部知识库 Provider 配置（ragflow / es_bm25）
 
-    KB_PROVIDER: Literal['ragflow', 'es_bm25'] = os.getenv('KB_PROVIDER', 'ragflow')  # type: ignore[assignment]
+    注意：必须在 `.env.*` 加载完成后再实例化读取，
+    所以使用 BaseSettings 而不是在 import 时读取环境变量。
+    """
+
+    KB_PROVIDER: Literal['ragflow', 'es_bm25'] = 'ragflow'  # type: ignore[assignment]
 
     # ES/OpenSearch
-    KB_ES_URL: str = os.getenv('KB_ES_URL', os.getenv('KB_OS_URL', '')).rstrip('/')
-    KB_ES_INDEX: str = os.getenv('KB_ES_INDEX', 'kb_chunks_v1')
-    KB_ES_USERNAME: str = os.getenv('KB_ES_USERNAME', '')
-    KB_ES_PASSWORD: str = os.getenv('KB_ES_PASSWORD', '')
-    KB_ES_VERIFY_SSL: bool = os.getenv('KB_ES_VERIFY_SSL', 'true').lower() == 'true'
+    KB_ES_URL: str = ''
+    KB_ES_INDEX: str = 'kb_chunks_v1'
+    KB_ES_USERNAME: str = ''
+    KB_ES_PASSWORD: str = ''
+    KB_ES_VERIFY_SSL: bool = True
 
     # retrieval
-    KB_TOP_K: int = int(os.getenv('KB_TOP_K', '8'))
-    KB_MIN_SCORE: float = float(os.getenv('KB_MIN_SCORE', '0'))
-    KB_MIN_COVERAGE: float = float(os.getenv('KB_MIN_COVERAGE', '0.2'))
-    KB_CACHE_TTL: int = int(os.getenv('KB_CACHE_TTL', '1800'))  # seconds
+    KB_TOP_K: int = 8
+    KB_MIN_SCORE: float = 0.0
+    KB_MIN_COVERAGE: float = 0.2
+    KB_CACHE_TTL: int = 1800  # seconds
 
     # fallback
-    KB_FALLBACK: Literal['ragflow', 'none'] = os.getenv('KB_FALLBACK', 'ragflow')  # type: ignore[assignment]
+    KB_FALLBACK: Literal['ragflow', 'none'] = 'ragflow'  # type: ignore[assignment]
+
+    def model_post_init(self, __context) -> None:  # type: ignore[override]
+        # 规范化：dotenv/环境变量可能带空格/大小写
+        provider = (str(self.KB_PROVIDER) if self.KB_PROVIDER is not None else 'ragflow').strip().lower()
+        self.KB_PROVIDER = provider if provider in ('ragflow', 'es_bm25') else 'ragflow'  # type: ignore[assignment]
+
+        es_url = (self.KB_ES_URL or '').strip().rstrip('/')
+        self.KB_ES_URL = es_url
+
+        fallback = (str(self.KB_FALLBACK) if self.KB_FALLBACK is not None else 'ragflow').strip().lower()
+        self.KB_FALLBACK = fallback if fallback in ('ragflow', 'none') else 'ragflow'  # type: ignore[assignment]
 
 
 class GetConfig: