目前国内支持离线下载的网盘没有几个了,也有些就是摆设,没用,所以就只能自己找方法了
如果你没有服务器,

http://ctrlq.org/save/

推荐,良心
支持google grive,one drive,dropbox,自建ftp server,box.net
看一下官方介绍
With Save, you can download any file from the web directly to your Dropbox, Google Drive or OneDrive accounts without having to download that file to your computer.

Just enter the file’s web address (or URL), pick a cloud service and, within seconds, the file will become available in your online account. The download is from cloud to cloud and therefore much faster.

Save is also useful for mobile users as you can remotely download files, including file types that aren’t supported by your mobile phone or tablet, to your mobile devices via Dropbox or Google Drive.

You can even transfer large files from the web to your FTP server directly.

首先需要授权一下Google账号才可以用(只是授权邮箱而已),输入你要下载的直接网址,然后选择你需要离线下载的地方,并且授权,就可以开始下载了。
ps 进度条好像是假的,如果是大文件,最后都会在99%的地方才开始下载,图片是可以秒存的。

http://urldroplet.com

不推荐 免费用户只有30m的容量限制,而且必须要注册。

如果你有服务器,那就简单多了,
直接直接挂载Google drive,也可以用命令行

PS 貌似Google也限制了下载速度
参考
http://blog.liaol.net/2014/04/dropboxoff/