var request = (HttpWebRequest)WebRequest.Create("URL");

             var data = Encoding.UTF8.GetBytes("username=zhenjinggu&md5Pwd=643d1820b9ce49bbf283b4875848596c&otpCode=");

             request.Method = WebRequestMethods.Http.Post;

             request.Timeout =  * ;

             request.AllowAutoRedirect = true;

             request.ContentLength = data.Length;

             request.ContentType = "application/x-www-form-urlencoded";

             request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";

             request.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.86 Safari/537.36";

             var stream = request.GetRequestStream();

             stream.Write(data, , data.Length);

             stream.Close();

             var response = (HttpWebResponse)request.GetResponse();

             var sr = new StreamReader(response.GetResponseStream());

             var content = sr.ReadToEnd();