Abstract: Based on the survey data of CFPS2018 (2018 China Family Panel Studies), this paper aims to explore the effect of the number of children and the supply of social security on the direction of intergenerational transfer. While taking into account the direction of intergenerational transfer, the demographic characteristics of parents and their children, and whether the elderly are covered by social security programs, the study finds that the number of children has a significant positive effect on the direction of economic intergenerational transfer as well as on the direction of care intergenerational transfer. Compared with the elderly who don't join any social security programs, those who are covered by old-age insurance are more likely to experience downward economic intergenerational transfers, while those who are covered by medical insurance are less likely to obtain upward economic intergenerational transfers, but are more likely to transfer care to their children, and those who enjoy other government subsidies are less likely to get economic transfers from their children. In addition, with the number of children as the mediating factor, whether the elderly have the medical insurance has a significant mediating effect on the downward economic intergenerational transfer, and whether they have other government subsidies has a significant mediating effect on the upward economic intergenerational transfer. Therefore, it is essential to implement the national three-child policy, develop and innovate the service model for the elderly, and build a high-quality social security system in the future.