Abstract: Strengthening the governance of school sports at the county level is a crucial foundation for accelerating the development of an education power and a healthy China, as well as a fundamental task in advancing the modernization of the national governance system and capabilities. Employing research methods such as comparative analysis and event history analysis, this study draws on policy diffusion theory to analyze the diffusion patterns, mechanisms, and models of national strategic school sports policies in county-level school sports governance. The analysis utilizes Kaplan-Meier survival functions, discrete-time event history models, and time-series event history models. The findings reveal the following: Temporally, policy diffusion in county-level school sports governance has been driven by critical junctures and phased planning agendas. Spatially, it exhibits a hierarchical pattern, transitioning from localized to widespread diffusion and from pioneering to follow-up adoption. From the discrete-time event history perspective, national policy diffusion at the county level is influenced by dual mechanisms—administrative directives and horizontal follow-up—under a holistic view, while heterogeneity analysis highlights the combined effects of administrative directives, vertical transmission, horizontal follow-up, and social construction mechanisms. The time-series event history analysis demonstrates that, under the influence of temporal and spatial factors, policy diffusion follows an intergovernmental regional follow-up model. This model prioritizes vertical transmission and horizontal follow-up mechanisms, supported by administrative directives and social construction mechanisms. Policy recommendations include: enhancing anticipatory governance to reduce diffusion costs; leveraging digital and intelligent technologies to improve diffusion efficiency; and aggregating limited resources to ensure policy implementation.