This study, based on the China Family Panel Studies (CFPS), and the construction of the CES (constant elasticity of substitution) production function with human capital, explores the non-linear relationship between parental investment and children’s cognitive and non-cognitive abilities in different periods. The findings show the following: In the children’s childhood, a crucial period for parental investment, parental investment had a significant and positive effect on the children’s human capital development, but as time went by, there was a gradual decrease in such an effect; parental investment in children’s childhood also played an important role in the development of children during their adolescence; according to different types of parental investment, the parents’ financial investment had a greater effect on their children’s early cognitive and non-cognitive abilities, but the parents’ time investment played an important role in the development of their children’s human capital during their adolescence; heterogeneity-based results showed that parental investment had a positive effect on disadvantaged children; counterfactual simulations proved that an early increase and a sustained increase in certain periods in parental investment could greatly improve the children’s cognitive and non-cognitive abilities; also, parental investment helped promote the long-term development of the children. Based on this, we need interventions aimed at improving the quality of family education to help parents establish scientific concepts of education and promote their children’s early accumulation of human capital, thus helping China shift from a populous country to a powerful country rich in human resources.