Do China people need a visa to go to Chiang Mai?

Need. According to relevant information, China citizens who hold China passports to Chiang Mai and then go to Hong Kong need to apply for a Hong Kong entry permit visa. According to the regulations of the Immigration Department of the HKSAR Government, China citizens need to apply for visas or entry permits through electronic channels (such as e-Pass) to enter Hong Kong. Specific application procedures and material requirements can be found on the website of the Immigration Department of the Government of the Hong Kong Special Administrative Region or consulted with relevant departments.