GridViewTOExcel...

 protected void Button1_Click(object sender, EventArgs e)
    {
        Response.ClearContent();
        Response.Charset = "gb2312";
        Response.ContentEncoding = System.Text.Encoding.UTF7;
        //Response.AddHeader("content=text/html,charset=GB2312");
        Response.AddHeader("content-disposition", "attachment;filename=MyExcel.xls");
        Response.ContentType = "application/excel";
        StringWriter sw = new StringWriter();
        HtmlTextWriter htw = new HtmlTextWriter(sw);
        this.GridView1.RenderControl(htw);
        Response.Write(sw.ToString());
        Response.End();
    }
    public override void VerifyRenderingInServerForm(Control control)
    {

    }
...