Can you use Shopify to build an e-commerce website in China? The short answer is yes but the long answer is depend.
Shopify is just like any websites or cloud services built outside China. All the traffic from China not international websites or services will need to pass through the Great Firewall of China (abbreviated to GFW). So loading international websites from within China is often much slower than it would be elsewhere. One common stumbling block is social media links, icons and widgets, as Facebook, Twitter, YouTube and Instagram are all blocked in mainland China as I write this, so linking to or using such widgets can result in a slower load time. There have also been some complaints that Google Fonts can slow down websites in China due to the restriction on Google's services there.
There is something we can do to speed up the site:
Remove all widgets or social media links that blocked by GFW
Not to load any external resources from Google e.g. google fonts or Google Hosted Libraries. Host it your own.
Shopify haven't CDN node in China that made the website resource load very slowly or open failed. You may consider using China Speed Up that can automatically migrates your Shopify website's resources to China CDN.
