Background The Chinese healthcare system faces a dilemma between its hospital-centric approach to healthcare delivery and a rapidly aging population that requires strong primary care. To improve system efficiency and continuity of care, the Hierarchical Medical System (HMS) policy package was implemented in 2015 in Zhejiang province, China. This paper investigated the impact of HMS on the local healthcare system.MethodsWe conducted a repeated cross-sectional study with quarterly data collected between 2010 and 2018 from Yinzhou district, Ningbo. The data was analyzed with an interrupted time series (ITS) design to assess the impact of HMS on the changes of three outcome variables: primary care physicians (PCPs) patient encounter ratio (i.e., the mean quarterly number of patient encounters of PCPs divided by that of all other physicians), PCP degree ratio (i.e., the mean degree of PCPs divided by that of all other physicians), PCP betweenness centrality ratio (i.e., the mean betweenness centrality of PCPs divided by that of all other physicians). Results272,267 patients visited doctors for hypertension between 2010 and 2018. Compared to the counterfactual in the fourth quarter of 2018, the PCP patient encounter ratio rose by 42.7% (95%CI: 27.1—58.2, p<0.001), the PCP degree ratio increased by 23.6% (95%CI: 8.6—38.5, p<0.01), and the PCP betweenness centrality ratio grew by 129.4% (95%CI: 87.1—171.7, p<0.001).ConclusionsThe HMS policy can incentivize patients to visit primary care facilities and enhance the centrality of PCPs within their professional network. Local policymakers should sustain HMS policy efforts to obtain long-term and large-scale benefits.