According to relevant information, it is illegal. The operation agreement is signed to fully guard against some accidents. So it is illegal not to sign. According to the Regulations on the Administration of Medical Institutions, medical institutions refer to hospitals, health centers, out-patient departments, clinics and health centers. After passing the examination by the administrative department of health, it is registered and issued a practice license for medical institutions. If you go to the usual beauty salon, the adverse consequences are not medical accidents, but ordinary infringement cases.