In China， the demand for social work in mental health care institutions has increased with the development of mental illness. Some mental health care institutions have set up social work departments and allocated professionals. Studies have shown that it is essential to clarify the role of social workers in mental health care institutions. Therefore， this paper reviews the research on social workers' functions in mental health institutions in China and abroad， and concludes that the main functions are prevention， psychosocial assessment， psychological support， crisis intervention and social resources seeking. This review provides reference for social work managers and clinical social workers in the field of mental health in China.