Can Vietnamese and China people immigrate to China when they get married?

Treat them differently. If you have been naturalized in China, you can; Otherwise, you can't People's Republic of China (PRC) nationality certificate and legal and stable residence certificate issued by the Ministry of Public Security are required. Take Hebei Province as an example.

"Regulations on Household Registration Management of Public Security Organs in Hebei Province"

Thirty-second foreigners or stateless persons who have been approved to be naturalized and those who have been approved to restore China nationality to declare their accounts shall go to the police station with the following materials:

(1) People's Republic of China (PRC) Nationality Certificate issued by the Ministry of Public Security;

(2) Proof of legally stable residence.