HTML：

RenderOuterTable="false" onauthenticate="LoginUser_Authenticate">





ValidationGroup="LoginUserValidationGroup"/>



CS文件注册一个事件外加一个赋值即可：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Account_Login : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
RegisterHyperLink.NavigateUrl = "Register.aspx?ReturnUrl=" + HttpUtility.UrlEncode(Request.QueryString["ReturnUrl"]);
}
protected void LoginButton_Click(object sender, EventArgs e)
{

}
protected void LoginUser_Authenticate(object sender, AuthenticateEventArgs e)
{
//此处省略代码200行
e.Authenticated = true;
}
}