Legal analysis: illegal. If you just do massage, you won't break any laws and you won't be detained. If your massage service involves other illegal services, you may be punished by public security and face fines and criminal detention.

Legal basis: Article 66 of the Law of People's Republic of China (PRC) on Public Security Punishment stipulates that a person who engages in prostitution or whoring shall be detained for more than 10 days and less than 15 days, and may also be fined less than 5,000 yuan; If the circumstances are minor, they shall be detained for not more than five days or fined not more than five hundred yuan.

Whoever solicits prostitutes in public places shall be detained for not more than five days or fined not more than 500 yuan.