用 document.readyState == "complete" 判断页面是否加载完成。

        function MyLoading(falg) {
            var loading = "<div id='dlading' style='position:absolute;left:0;100%;height:100%;top:0;background:#FFFFFF;opacity:0.8;filter:alpha(opacity=90);'>";
            loading += "<div style='border:2px solid #B7CDFC;position:absolute;cursor:wait;left:50%;top:50%;200px;height:32px;line-height:28px;text-indent:36px;font-size:14px;background:#fff url(Content/css/images/loading.gif) no-repeat left center;'>";
            loading += "正在加载，请等待......</div></div>";
            if (falg) {
                $("body", document).append(loading);


            } else {
                if ($("#dlading") != undefined) {
                    $("#dlading").remove();
                }
            }
        }

                    $(document).ready(function () {
            MyLoading(true);
            if (document.readyState == "complete") {
                MyLoading(false);
            }
            if (document.readyState == "complete") {
                MyLoading(false);
            }
            else {
                document.onreadystatechange = function () {
                    if (document.readyState == "complete") {
                        MyLoading(false);
                    }
                }
            }
})