private void btn_out_Click(object sender, System.EventArgs e)
{
DgToExcel(dg_sj,"noname.xls");
}

public void DgToExcel(System.Web.UI.Control ctl,string str)
{
// HttpContext.Current.Response.Charset ="GB2312";
HttpContext.Current.Response.Charset ="";
HttpContext.Current.Response.AppendHeader("Content-Disposition","attachment;filename=" + str);

HttpContext.Current.Response.ContentEncoding =System.Text.Encoding.GetEncoding("GB2312");
HttpContext.Current.Response.ContentType ="application/ms-excel";//image/JPEG;text/HTML;image/GIF;vnd.ms-excel/msword
ctl.Page.EnableViewState =false;
System.IO.StringWriter tw = new System.IO.StringWriter() ;
System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter (tw);
ctl.RenderControl(hw);
HttpContext.Current.Response.Write(tw.ToString());
HttpContext.Current.Response.End();
}