使用其他TextBox的Validating事件，此处，仅在用户完成操作后执行代码输入密码.

Use the Validating event of other TextBox, here, the code is only executed when the user has finished entering the password.

您可以使用其他方法，但不能使用textChange来检查两个密码
例如，您可以在method下创建并在button_click中调用它；

you can use another method but no textChange for check two password
for example you can make under method and in button_click call it;

 public  void CheckTwoPassword(string textbox1,string  textbox2)
{
 if(textbox1==textbox2)
  {
    //do some work 
  }
}

然后您的按钮点击

and your button click

public void Button_Click(sender s,object o)
{
 CheckTwoPassword(textbox1.text,textbox2.text);
}

您可以在第二个文本框的"Leave"或"LostFocus"事件中比较密码

Hi,
You can compare passwords in "Leave" or "LostFocus" event of the second textbox