Abstract: Since the founding of the People's Republic of China, the two strategies of "investment in physical capital" and "investment in human capital" have been interdependent and dialectically unified, with their interactive evolution as a key driver of national development. Over the past seven decades, their relationship has undergone four main stages: a "physical-capital-led human development" stage centered on heavy industries under the planned economy; a "quantitative emphasis on human capital" stage during industrial restructuring under the early reform and opening-up; a "coordinated investment in both physical and human capital" stage amid the deepening of market-oriented reforms; and a current "synergistic integration" stage guided by high-quality development. This evolutionary trajectory reflects the dynamic adaptation and self-improvement of national development strategies in response to shifting domestic and international contexts and changing principal social contradictions at different historical stages. China's practice has transcended the traditional "welfare versus efficiency" dichotomy, forging a people-centered sustainable development path that reinforces both equity and efficiency. This approach has laid a critical foundation for advancing common prosperity and socialist modernization.