As of January 6, 2021, the Government of Canada has put in place additional emergency measures to slow the spread of COVID-19. The official government policy can be found on the Government of Canada site here.
Those returning to Canada (5 years of age or older) are required to provide proof of a negative COVID-19 molecular test taken, at their own expense, no more than 72 hours before the aircraft’s initial scheduled departure time.
The approximate cost of a COVID-19 test in China is about 120RMB. As Canada does not have an entry application (QR) like China, printing out a copy (or several) would be a good idea.
You will also need to submit a quarantine plan electronically before boarding a plane to Canada on the ArriveCan App or website.
The Government of Canada and Global News have good guides to re-entering Canada.