Use Chinese CDN (such as Upyun, Baidu CDN, Qiniu and Aliyun) for http file downloading (with a subdomain provided by the CDN or you'll need to apply permissions at MIIT as ICP) instead of rsync or ssh tunnel. Or rsync your data to Japanese Servers (Linode, GMO, etc) and ask your customers to download through http or https.
The problem is to upload data to China, we are not downloading anything from there.
"Or rsync your data to Japanese Servers (Linode, GMO, etc) and ask your customers to download through http or https."
We've used Amazon CDN before even for Chinese customers and they have closest node in Hong Kong - they still(Chinese) have difficulties to download our packages. I doubt using Japanese server would solve our problem. Thanks anyway.