var myParent = parent.parent.parent.parent.parent.parent.parent.parent.parent.parent.parent.parent;
FileDown = function (fileName, realFileName) {
    $(myParent.document.body).find("#down-file-iframe").remove();
    var $iframe = $('<iframe name="_down-file-iframe" id="down-file-iframe" style="position:absolute;top:-10000px;left:-10000px;"></iframe>');
    var $a = $('<a href="' + fileName + '">下載</a>');
    if (realFileName != null)
    { $a.attr("download", realFileName); }

    $(myParent.document.body).append($iframe);

    $iframe[0].onload = $iframe[0].onreadystatechange = function () {
        var titleElem = $(this.contentWindow.document).find("title");
        if (titleElem.length > 0) {
            if (titleElem.text().indexOf("404") >= 0)
            { myDialog({ title: "提示", content: "檔案下載失敗：<br/>" + "該檔案不存在或已被刪除" }); }
            else
            { myDialog({ title: "提示", content: "檔案下載失敗：<br/>" + titleElem.text() }); }
          
        }
    }

    var DataExport_Timer = setInterval(function () {
        var iframeObj = myParent.window.frames["down-file-iframe"].contentWindow || myParent.window.frames["down-file-iframe"];

        if ($(iframeObj.document.body).length <= 0) { return; }

        clearInterval(DataExport_Timer);
        $(iframeObj.document.body).append($a);
        $a[0].click();
        setTimeout(function () { $iframe.remove(); }, 1000 * 120);
    }, 200);
}

　　如果是彈出框形式的話，把此方法放在父窗體的頁面，實現下載檔案

呼叫

//遍歷下載多個檔案
            for (var i = 0; i <= ids.length; i++) {
                $.ajax({
                    url: '/Apply/DownloadScanFile',
                    cache: false,
                    async: false,
                    type: 'post',
                    data: { id: ids[i] },
                    success: function (data) {
                        //CloseDialog();
                        if (data.Status == 1) {
                            FileDown(data.FullFileName, data.FileName);
                        } else {
                            myDialog({ title: "提示", content: data.Error });
                        };
                    }
                });

            }

　　控制器

 /// <summary>
        /// 下載回覆檔案
        /// </summary>
        /// <param name="ids"></param>
        /// <returns></returns>
        public JsonResult DownloadFile(int id)
        {

            var model = Db.GetApplyResultFile(id);
            return Json(new { Status = 1, FullFileName = "\\" + model.FilePath, FileName = model.FileName });
        }