string postData = "user=123&pass=456"; // 要发放的数据
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
HttpWebRequest objWebRequest = (HttpWebRequest)WebRequest.Create("http://www.abc.com/a.aspx");
objWebRequest.Method = "POST";
objWebRequest.ContentType = "application/x-www-form-urlencoded";
objWebRequest.ContentLength = byteArray.Length;
Stream newStream = objWebRequest.GetRequestStream();
// Send the data.
newStream.Write(byteArray, 0, byteArray.Length); //写入参数
newStream.Close();
HttpWebResponse response = (HttpWebResponse)objWebRequest.GetResponse();
StreamReader sr=new StreamReader(response.GetResponseStream(), Encoding.Default);
string textResponse = sr.ReadToEnd(); // 返回的数据
原文http://zhidao.baidu.com/question/89976700.html