Based on the four-wave panel data from the China Health and Retirement Longitudinal Study（CHARLS） in 2011－2018，using a causal identification strategy combining fixed-effects modeling and instrumental variable methods， this article empirically examines the effects of grandparenting on physical and mental health of rural grandparents and its gender difference.We also investigate the moderating role of living arrangement in the relationship between grandparenting and the health of grandparents and further explores the potential mechanism pathways of grandparenting effects on the health of grandparents.Overall，we find that grandparenting had a significant negative impact on both physical and mental health of rural grandparents. Specifically，high-intensity caregiving is more likely to have a significant adverse impact on the physical and mental health of grandparents compared with low-intensity caregiving. The negative health effect of grandparenting is higher among grandmothers than grandfathers. Not co-residence with children but co-residence with grandchildren could reinforce the negative health effect of grandparenting，while co-residence with children could significantly alleviate the negative health effect.The above moderation effect of living arrangements is more significant among grandmothers. Promoting social participation and increasing intergenerational economic support are two important channels to mitigate the negative health effect of grandparenting.Given increasingly prevalent grandparenting in rural areas of China，future policies can be implemented to promote positive aging and healthy aging for rural grandparents. First，more public childcare services need to be provided to alleviate the intensity for rural grandparents and help them care for their grandchildren.Second，as the most vulnerable group，rural grandmothers need to be given more training on childcare and health promotion intervention.Third，the institutional barriers should be removed to help migrant children live with their parents in cities and reduce the proportion of rural skip-generation households.Fourth，it is useful to encourage the rural parents to provide grandparents more economic and emotional support through cultural advocacy and institutional incentives.