您需要为上传的文件定义一个具有如下属性的模型，它的类型应为HttpPostedFileBase。

public class UploadModel
{
    [Required(ErrorMessage="Please choose a file to upload.")]
    public HttpPostedFileBase Photo { get; set; }
}

然后，您需要执行接受指定模型并返回JavaScript（而不是View）的操作。

public ActionResult Upload(UploadModel model)
{
    //only continue if the model is valid (i.e. all the required fields have been set)
    if (ModelState.IsValid)
    {
        string json = "";//build your JSON here
        //return the JSON as a javascript response (with the correct headers, etc)
        return JavaScript(json);
    }

    return View(model);
}

(function() {
    window.App = {
        Router: {}
        View: {}
    };

    App.Router = Backbone.Router.extend({

        routes: {
            '*AreaName/admin/import/upload': 'upload'
        },

        upload: function() {
            var upload= new App.View.upload();
        },

    });

    $(document).ready(function() {
        window.routes = new App.Router;
        Backbone.history.start({ pushState: true });
    });

})();