Chinese student travelling from Canada to Nepal stopping in Hong Kong for a day - Need Visa?

Yes, Chinese passport holders need to obtain an entry permit from Chinees embassy or consulate in advance.

I also sent an email to the Immigration Dept of the Govt of Hong Kong who replied differently, here is the answer I received from the Director of Immigration;

Chinese passport holders who are in transit through Hong Kong to and from another country or territory (e.g. Canada » HKSAR » Mainland China and Mainland China » HKSAR » Canada or Canada » HKSAR » Nepal ) may be granted a stay of seven days on each landing without the prior need to obtain an entry permit provided that usual immigration requirements are met, including possession of adequate funds to cover the duration of stay in Hong Kong, possession of valid entry facilities for the destination and unless in transit to Mainland of China, the holding of confirmed onward booking for the overseas journey.
This entry-permit-free transit arrangement aims to facilitate their overseas travel to and from Mainland of China by enabling them to connect flights or stopover in Hong Kong.

Hi Jocelyn, the answer by Immigration Dept is correct. Chinese passport holders are allowed free stay of 7 days for transit.