Objective To systematically assess the impact of comprehensive medical reform on the supply of primary healthcare resources in China, providing evidence to inform the optimization of national healthcare reform policies.

Methods Using data from sources such as the China Health and Family Planning Statistical Yearbook, China Health Statistical Yearbook, and China Fiscal Yearbook, we constructed a provincial panel data set of China from 2012 to 2020. Treating China′s pilot comprehensive reform as a quasi-natural experiment, we developed a multi-period difference-in-differences (DID) model to systematically evaluate the impact of the reform on primary healthcare resource supply across the dimensions of scale, structure, and accessibility. Additionally, we conducted thematic analysis of semi-structured interviews with 30 key informants from six provinces (Zhejiang, Guangdong, Hunan, Henan, Sichuan, and Yunnan) to validate and deepen the quantitative findings.

Results The multi-period DID model showed that the comprehensive medical reform increased the number of healthcare personnel per thousand population at the primary level (β = 0.079, P = 0.046) and the number of registered nurses per thousand population at the primary level (β = 0.045, P = 0.001). The structural proportions of healthcare personnel and registered nurses at the primary level (β = 0.006, P = 0.088; β = 0.009, P = 0.01) and the accessibility (β = 0.038, P = 0.014; β = 0.085, P = 0.001) were also significantly improved. The thematic analysis of semi-structured interviews revealed that comprehensive medical reform influenced the supply of primary healthcare resources through five mechanisms: allocation, resource distribution, governance structure, technology application, and institutional design, whereas policy coordination and systemic reform limitations constrained the overall effectiveness.

Conclusions Comprehensive medical reform significantly improves the structure and accessibility of primary healthcare resources in China. However, shortages of primary-level physicians remain. Future efforts should focus on establishing a long-term governance mechanism for an integrated primary healthcare resource supply system, moving from pilot points to multiple simultaneous implementations and from fragmented initiatives to systematic integration, thereby supporting the high-quality development of the Healthy China initiative.