asp.net code：

ClientScript.RegisterStartupScript(Page.GetType(), "", "<script language=javascript>CloseWebPage();</script>");

js code：

优化版（当window.close()无效时，跳转空页面）

window.opener = null;
window.open('', '_self', '');
window.close();
window.location.href = 'about:blank ';

(原版参考文章

<script type="text/javascript">  
    function CloseWebPage() {  
        if (navigator.userAgent.indexOf("MSIE") > 0) {  
            if (navigator.userAgent.indexOf("MSIE 6.0") > 0) {  
                window.opener = null; window.close();  
            }  
            else {  
                window.open('', '_top'); window.top.close();  
            }  
        }  
        else if (navigator.userAgent.indexOf("Firefox") > 0) {  
            window.location.href = 'about:blank ';  
            //window.history.go(-2);  
        }  
        else {  
            window.opener = null;   
            window.open('', '_self', '');  
            window.close();  
        }  
    }  
</script>