China’s one-child policy since 1979 had an exogenous impact on the maternity security of “raising children for old age”, therefore, the current policy goals should guide groups to voluntarily transition from family pension to the social pension. Based on micro data from China Family Panel Studies (CFPS), this paper takes China’s New Rural Pension Scheme (NRPS) as an example, and employs a fuzzy regression discontinuity design to examine the effects of the one-child policy on the NRPS participation decision of the rural people. Empirical results show that the one-child policy has significantly enhanced the NRPS participation. And the policy effects are prominent among households with disadvantaged capital endowment, in the Midwest and the region where the one-child-and-a-half policy was not implemented. Furthermore, we exploit the potential mechanisms and find that the policy-induced one-child parents have a lower probability of having a boy offspring, less income in old age, and worse health conditions, which could prompt them from family pension to social pension. In the context of population aging, considering the structural decrease in the maternity security of one-child parents, the financial transfer can be used to compensate for intergenerational economic transfers and ease the pension pressure on one-child parents, which is conducive to improving people’s well-being and promoting social justice.