diff --git a/api/apps/user_app_fastapi.py b/api/apps/user_app_fastapi.py
index 6e4d9e9..0cefc5c 100644
--- a/api/apps/user_app_fastapi.py
+++ b/api/apps/user_app_fastapi.py
@@ -125,12 +125,13 @@ async def login(request: LoginRequest):
     """
     用户登录端点
     """
-    email = request.email
-    users = UserService.query(email=email)
+    raw_email = (request.email or "").strip()
+    email = raw_email.lower()
+    users = UserService.query_user_by_email_insensitive(raw_email)
     if not users:
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
-            detail=f"Email: {email} is not registered!"
+            detail=f"Email: {raw_email} is not registered!"
         )
 
     password = request.password
diff --git a/api/db/services/user_service.py b/api/db/services/user_service.py
index 00fb837..a1c8a57 100644
--- a/api/db/services/user_service.py
+++ b/api/db/services/user_service.py
@@ -18,6 +18,7 @@ from datetime import datetime
 import logging
 
 import peewee
+from peewee import fn
 from werkzeug.security import generate_password_hash, check_password_hash
 
 from api.db import UserTenantRole
@@ -93,8 +94,15 @@ class UserService(CommonService):
         Returns:
             User object if authentication successful, None otherwise.
         """
-        user = cls.model.select().where((cls.model.email == email),
-                                        (cls.model.status == StatusEnum.VALID.value)).first()
+        normalized_email = (email or "").strip().lower()
+        user = (
+            cls.model.select()
+            .where(
+                fn.Lower(cls.model.email) == normalized_email,
+                cls.model.status == StatusEnum.VALID.value
+            )
+            .first()
+        )
         if user and check_password_hash(str(user.password), password):
             return user
         else:
@@ -106,6 +114,16 @@ class UserService(CommonService):
         users = cls.model.select().where((cls.model.email == email))
         return list(users)
 
+    @classmethod
+    @DB.connection_context()
+    def query_user_by_email_insensitive(cls, email):
+        normalized_email = (email or "").strip().lower()
+        users = (
+            cls.model.select()
+            .where(fn.Lower(cls.model.email) == normalized_email)
+        )
+        return list(users)
+
     @classmethod
     @DB.connection_context()
     def save(cls, **kwargs):