diff --git a/api/routers/auth.py b/api/routers/auth.py
index 65b9ec5..697d72c 100644
--- a/api/routers/auth.py
+++ b/api/routers/auth.py
@@ -100,6 +100,11 @@ class ChangePhoneRequest(BaseModel):
     code: str = Field(..., min_length=6, max_length=6, description="验证码（6位）")
 
 
+class UpdateNicknameRequest(BaseModel):
+    """更新昵称请求"""
+    nickname: str = Field(..., min_length=1, max_length=50, description="昵称（1-50个字符）")
+
+
 # 响应模型
 class TokenResponse(BaseModel):
     """令牌响应"""
@@ -659,25 +664,21 @@ async def login_with_sms(
     
     # 如果用户不存在，自动注册
     if not user:
-        # 注册时需要提供昵称
-        if not request.nickname or len(request.nickname.strip()) == 0:
-            raise HTTPException(
-                status_code=status.HTTP_400_BAD_REQUEST,
-                detail="首次登录需要设置昵称"
-            )
-        
         # 创建新用户
         user_id = str(uuid.uuid4())
         # 生成一个随机密码（用户不会用到，但数据库要求必填）
         random_password = secrets.token_urlsafe(32)
         password_hash = hash_password(random_password)
         
+        # 如果提供了昵称就使用，否则使用空字符串（表示需要后续设置）
+        nickname = request.nickname.strip() if request.nickname else ""
+        
         user = User(
             id=user_id,
             phone=request.phone,
             password_hash=password_hash,
             email=None,
-            nickname=request.nickname.strip(),
+            nickname=nickname,
             subscription_type="free",
             created_at=datetime.now(timezone.utc)
         )
@@ -922,6 +923,33 @@ async def change_phone(
     )
 
 
+@router.put("/me/nickname", response_model=UserResponse)
+async def update_nickname(
+    request: UpdateNicknameRequest,
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_async_db)
+):
+    """
+    更新用户昵称
+    
+    用于首次登录后设置昵称，或修改现有昵称
+    """
+    # 更新昵称
+    current_user.nickname = request.nickname.strip()
+    await db.commit()
+    await db.refresh(current_user)
+    
+    return UserResponse(
+        id=current_user.id,
+        phone=current_user.phone,
+        email=current_user.email,
+        nickname=current_user.nickname,
+        avatar_url=current_user.avatar_url,
+        subscription_type=current_user.subscription_type,
+        created_at=current_user.created_at.isoformat()
+    )
+
+
 @router.post("/logout/all")
 async def logout_all_devices(
     current_user: User = Depends(get_current_user),