public void ToExcel(System.Web.UI.Control ctl)  
        {            
            HttpContext.Current.Response.AppendHeader("Content-Disposition","attachment;filename=DayReport.xls");
            HttpContext.Current.Response.Charset ="UTF-8";                
            HttpContext.Current.Response.ContentEncoding =System.Text.Encoding.Default;
            HttpContext.Current.Response.ContentType ="application/ms-excel";
            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();
        }

调用

ToExecel(DataGridName);

HttpContext.Current.Response.ContentType ="application/ms-excel";
HttpContext.Current.Response.AppendHeader("Content-Disposition","attachment;filename="+""+FileName+".xls");
System.IO.StringWriter  tw = new System.IO.StringWriter();
System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
this.DataGrid1.RenderControl(hw);
HttpContext.Current.Response.Write(tw.ToString());
HttpContext.Current.Response.End();