private void Button1_Click(object sender, System.EventArgs e)
  {
   string PageUrl = flyso.aspx" target="_blank" rel="external">http://localhost/Application/flyso.aspx;
   //你要生成的ASPX文件
   System.Net.WebRequest request = System.Net.WebRequest.Create(PageUrl);
   System.Net.WebResponse response = request.GetResponse();
   System.IO.Stream resStream = response.GetResponseStream();
   System.IO.StreamReader sr = new System.IO.StreamReader(resStream, System.Text.Encoding.UTF8);
   ContentHtml.Text = sr.ReadToEnd();
   resStream.Close();
   sr.Close();
   string filename=System.DateTime.Now.ToString("yyyyMMddHHmmss");
   System.IO.StreamWriter sw=new   System.IO.StreamWriter("c:/"+filename+".htm",false,System.Text.Encoding.UTF8); //最后一个参数视实际需要  

   sw.WriteLine(ContentHtml.Text);  
   sw.Close();  
   Response.WriteFile("c:/"+filename+".htm");
  }

if (Request.QueryString["toHtml"] == null)
        {
            
            System.IO.StringWriter sw = new System.IO.StringWriter();
            Server.Execute("default.aspx?toHtml=1",sw);
            System.IO.StreamWriter stremwriter = new System.IO.StreamWriter(Server.MapPath("aa.html"),false,System.Text.Encoding.Default);
            stremwriter.Write(sw.ToString() );

            stremwriter.Close();
            Response.Redirect("aa.html");

        }