Negative life events largely affect older adults’ mental health and thus should be understood and addressed carefully to improve the life quality of the elderly. Based on the socioemotional selectivity theory, and using the data of 2014 China Longitudinal Aging Social Survey, this paper analyzes the impacts of negative life events on Chinese older adults’ mental health, and explores the moderating effects of social networks and coping styles. The results show that, during the year before the survey, 28% of the Chinese elderly have experienced at least one negative life event. This experience is negatively correlated with the mental health of the elderly. The results from multiple regression analysis suggest that family network, friend network and active coping style have a positive effect on mental health, while negative coping will adversely influence the mental health of older adults. Therefore, both the internal coping style of the elderly and external network resources, especially the family supports, should be promoted to reduce the harmful effects of negative events on older adults’ mental health.