Abstract: Based on the balance panel data of China Health and Retirement Longitudinal Study(CHARLS),in 2011 and 2015,the DID method was used to analyze the substitute effect of economic support and medical supply for the children of rural left-behind elderly by rural social insurance based on new rural insurance and new rural cooperative medical insurance.Empirical research finds that the economic support and medical supply provided by the New Rural Insurance and New Rural Cooperative Medical Care for their children are lower.The New Rural Cooperative Medical Care can increase their medical participation rate and reduce their medical worries to a certain extent.At the same time,based on the heterogeneity discussion,it is further found that the lower the individual(family)security ability is,the more obvious the substitute effect of the New Rural Insurance and New Rural Cooperative Medical Care for the care of their children will be.Therefore,it is necessary to increase the economic and medical welfare effects of social insurance policies such as the New Rural Insurance and the New Rural Cooperatives on the rural left-behind elderly,on the basis of effectively improving the standard and scope of policy subsidies,focus on the elderly care and medical dilemma of rural left-behind groups,and implement targeted preferential policies.

Key words: New Rural Insurance, New Rural Cooperative Medical Care, economic support, medical supply, DID