///<summary>
        /// 根據 Agent 判斷是否是智能手機
        ///</summary>
        ///<returns></returns>
        public static bool IsMobileDevice()
        {
            bool flag = false;

            string agent = HttpContext.Current.Request.UserAgent;
            //_log.Debug(string.Format("判斷是否是智能手機，UserAgent：{0}", agent));
 

            string[] keywords = { "Android", "iPhone", "iPod", "iPad", "Windows Phone", "MQQBrowser", "IUC", "UCWEB", "JUC" };

            //排除 Windows 桌面系統
            if (!agent.Contains("Windows NT") || (agent.Contains("Windows NT") && agent.Contains("compatible; MSIE 9.0;")))
            {
                
 
//排除 蘋果桌面系統
                if (!agent.Contains("Windows NT") && !agent.Contains("Macintosh"))
                {
                    foreach (string item in keywords)
                    {
                        if (agent.Contains(item))
                        {
                            flag 
 
= true;
                            break;
                        }
                    }
                }
            }

            return flag;
        }

Request.Browser.IsMobileDevice

這兩個都可以判斷是手機登錄還是PC登陸，可以參考

判斷是否為手機網站