CookieContainer cookies = new CookieContainer();

            string url = "http://www.google.com.hk/";

            HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);

            myHttpWebRequest.Timeout = 20 * 1000; //连接超时

            myHttpWebRequest.Accept = "*/*";

            myHttpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0;)";

            myHttpWebRequest.CookieContainer = new CookieContainer(); //暂存到新实例

            myHttpWebRequest.GetResponse().Close();

            cookies = myHttpWebRequest.CookieContainer; //保存cookies

            string cookiesstr = myHttpWebRequest.CookieContainer.GetCookieHeader(myHttpWebRequest.RequestUri); //把cookies转换成字符串

            url = "http://www.google.com.hk/search?oe=utf8&ie=utf8&source=uds&hl=zh-CN&q=3g";

            myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);

            myHttpWebRequest.Timeout = 20 * 1000; //连接超时

            myHttpWebRequest.Accept = "*/*";

            myHttpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0;)";

            myHttpWebRequest.CookieContainer = cookies; //使用已经保存的cookies 方法一

            //myHttpWebRequest.Headers.Add("Cookie", cookiesstr); //使用已经保存的cookies 方法二

            HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse();

            Stream stream = myHttpWebResponse.GetResponseStream();

            stream.ReadTimeout = 15 * 1000; //读取超时

            StreamReader sr = new StreamReader(stream, Encoding.GetEncoding("utf-8"));

            string strWebData = sr.ReadToEnd();

            richTextBox1.Text = cookiesstr  +"rnrn"+ strWebData;