Despite the crackdown on cryptocurrencies, Chinese traders are still trading them with Virtual Private Networks (VPNs).
Well they banned cryptocurrency exchanges. Most people can still take the exchange outside of the country to trade (eg. in Hong Kong). Even though there is a ban, you have to consider that China is investing a lot into Blockchain, the backbone to cryptocurrencies. Also, 2/3 of the crypto mining operations is within China, so you have to consider, China holds a huge amount of power within cryptocurrency if the government there decides to stop the ban on the exchange.