In the new era of preferentially developing agriculture and rural areas，more attention should be paid to health of rural China’s residents to achieve universal health. Based on data of CHARLS，this paper discusses the effect of the social health insurance on the mental health of the middle-aged and aged residents in rural China by adopting two dependent variables of mental depression and cognitive health. The results reveals that health insurance significantly promotes the mental health of the insured residents，especially the vulnerable groups. The heterogeneity test indicates that the influence of health insurance on mental depression is significant in male people，group of people aged 60 years or more，low-income groups and residents live in rural areas. Quantile regression and regression after changing dependent variable proves the robustness of conclusions. The paper also tests the possible mechanisms that health insurance positively influences mental health by strengthening the insured residents’ safety expectation and life satisfaction. Hence，it’s necessary to further extend coverage of the health insurance system，improve institutional equity to increase the safety expectation of the rural residents，expand government spending on countryside and stress health education to break the predicaments of low interest on both sides of supply and demand，thus fundamentally promote the mental health of the rural residents.