http://social.microsoft.com/Forums/es-ES/295/thread/5c7c219c-f41f-49ca-b74d-ef71c6d2f06b
自行解决,
function afteradd() {
var div = document.getElementById('gvdiv');
div.scrollTop = div.scrollHeight;
}
增加完行后执行
ScriptManager.RegisterStartupScript(this, this.GetType(), "", "<script language='javascript'>afteradd();</script>", false);