diff --git a/models.py b/models.py
index 64b5a60..7349a54 100644
--- a/models.py
+++ b/models.py
@@ -100,11 +100,19 @@ class User(db.Model):
         return False
 
     def is_active(self):
-        """用户是否可用（未过期、未封禁、已启用）"""
+        """用户是否可用（未过期、未封禁、已启用）
+
+        SQLite 不存 tzinfo, 从数据库读出的 datetime 是 naive;
+        我们统一当作 UTC 处理后再比较, 避免 aware/naive TypeError.
+        """
         if not self.enabled or self.banned:
             return False
-        if self.expire_at and datetime.now(timezone.utc) > self.expire_at:
-            return False
+        if self.expire_at:
+            exp = self.expire_at
+            if exp.tzinfo is None:
+                exp = exp.replace(tzinfo=timezone.utc)
+            if datetime.now(timezone.utc) > exp:
+                return False
         return True
 
     def __repr__(self):
diff --git a/services/user_service.py b/services/user_service.py
index a7a127f..6fe0a2b 100644
--- a/services/user_service.py
+++ b/services/user_service.py
@@ -15,6 +15,39 @@ _FAIL2BAN_MAX = 10
 _FAIL2BAN_WINDOW = 600
 
 
+def _parse_expire_at(value):
+    """从 HTML form / API JSON 接收 expire_at, 转成 UTC-aware datetime 或 None.
+
+    支持:
+    - None / 空字符串 -> None
+    - ISO 字符串 (含 'T' 或 ' ') -> datetime (UTC)
+    - 已经是 datetime 的 -> 视为 UTC (如果是 naive 就补 tz)
+    - 非法格式 -> None
+    """
+    if not value:
+        return None
+    if isinstance(value, datetime):
+        return value if value.tzinfo else value.replace(tzinfo=timezone.utc)
+    s = str(value).strip()
+    if not s:
+        return None
+    # HTML datetime-local 格式 "2026-12-31T23:59" 或 "2026-12-31 23:59"
+    for fmt in ("%Y-%m-%dT%H:%M:%S", "%Y-%m-%dT%H:%M", "%Y-%m-%d %H:%M:%S", "%Y-%m-%d %H:%M"):
+        try:
+            dt = datetime.strptime(s, fmt)
+            return dt.replace(tzinfo=timezone.utc)
+        except ValueError:
+            continue
+    # ISO 完整格式 (fromisoformat 自动处理 tzinfo)
+    try:
+        dt = datetime.fromisoformat(s.replace("Z", "+00:00"))
+        if not dt.tzinfo:
+            dt = dt.replace(tzinfo=timezone.utc)
+        return dt
+    except ValueError:
+        return None
+
+
 class UserService:
     """用户管理服务。"""
 
@@ -66,6 +99,9 @@ class UserService:
             }
 
     def create_user(self, username, password="", **kwargs):
+        # expire_at 在 web form 里是字符串 (datetime-local), 转成 datetime
+        if "expire_at" in kwargs:
+            kwargs["expire_at"] = _parse_expire_at(kwargs["expire_at"])
         with db.app.app_context():
             if db.session.query(User).filter_by(username=username).first():
                 return {"error": "用户名已存在"}
@@ -78,6 +114,9 @@ class UserService:
             return {"id": u.id}
 
     def update_user(self, uid, **kwargs):
+        # expire_at 字符串转 datetime
+        if "expire_at" in kwargs:
+            kwargs["expire_at"] = _parse_expire_at(kwargs["expire_at"])
         with db.app.app_context():
             u = db.session.query(User).get(uid)
             if not u: