In this article，the author provides a systematic review of the research on the mental health issues of the middle-aged，namely the sandwich generation. The author mainly reviews and criticizes the literatures on the subject from two perspectives，stress theory and role theory. In addition，the author also reviews the research from the impact of social structure factors on mental health of the sandwich generation，including status groups，life span and gender. Finally，the author discusses the implications of the research for our understanding on the issue of mental health.