string sampleRequest = @"
<?xml version=""1.0""?>
你的节点
";
this.Response = ReceiveData(sampleRequest, Server);

            // Load Xml into a XmlDocument object
            XmlDocument XmlResponse = new XmlDocument();
            try
            {
                XmlResponse .LoadXml(this.Response);
            }
            catch
            {
            }

private string ReceiveData(string req, string Server)
        {
            ASCIIEncoding encoding = new ASCIIEncoding();
            byte[] data = encoding.GetBytes(req); // Request
            HttpWebRequest r = (HttpWebRequest)WebRequest.Create(Server); 
            r.Method = "POST";
            r.ContentType = "application/x-www-form-urlencoded";
            r.ContentLength = data.Length;
            Stream requestStream = r.GetRequestStream();
            r.Write(data, 0, data.Length);
            r.Close();
            WebResponse myResponse = null;
            string response;
            try
            {
                myResponse = r.GetResponse();
                using (StreamReader sr = new StreamReader(myResponse .GetResponseStream()))
                {
                    response = sr.ReadToEnd();
                    sr.Close();
                }
            }
            catch (Exception exc)
            {
                response = exc.ToString();
            }

            return response;
        }