这是我的代码 希望众大神帮忙看看 有问题不
protected void LinkButton1_Click1(object sender, EventArgs e)
    {
        LinkButton l = sender as LinkButton;
        DownLoad();
    }
    public void DownLoad()
    {
        string filepath = Server.MapPath("~") + "/" + l.ToolTip.Substring(2, l.ToolTip.Length - 2);
        if ((filepath))
        {
            FileInfo file = new FileInfo(filepath);
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8");
            Response.AddHeader("Content-Disposition", "attachment;filename=+=Server.UrlEncode(file.Name)");
            Response.AddHeader("Content-Disposition", file.Length.ToString());
            Response.ContentType = "application/octet-stream";
            Response.WriteFile(file.FullName);
            Response.End();
        }
    }

谢谢啦  查出来了 是路径的问题