Abstract: Objective To compare the mental health status and its influencing factors among permanent and floating population in Guangzhou for the promotion of mental health.Methods Convenience sampling was used to investigate 613 permanant residents and 258 floating persons in Guangzhou city.Results The overall scores of social support for permanent and floating population were 60.11±11.39 and 57.21±13.33.The scores of family support,friendly support,and other support for permanent population were higher than those of floating population (P<0.05 for all).Mental health status of permanent population was better than that of floating population.The WHO-5 Well-Being Index for permanent population was 15.93±5.39,higher than that of floating population (14.19±4.81). Results of logistic regression analyses showed that type of household registration,self-assessment of health,social support were influencing factors of mental health for the residents.Conclusion Wihtout local residence registration is a risk factor of low mental health status and good self-assessment health and social support are protective factors of mental health among the residents of Guangzhou.