["Transactions in GIS, Volume 30, Issue 4, June 2026. ", "\nABSTRACT\nUrban parks play a critical role in promoting sustainable and harmonious urban development. This research focuses on the accessibility of parks in urban core areas by integrating multi‐source data, redefining park supply capacity, fitting decay functions using trajectory data, and incorporating multimodal transportation. Based on these improvements, the 3‐step floating catchment area based on multi‐source data (MSD‐3SFCA) method is proposed. The results indicate that the MSD‐3SFCA method provides a more objective and robust assessment of park accessibility in urban core areas, effectively capturing the impacts of transportation barriers and population distribution. Higher levels of park accessibility are observed under driving and cycling modes. By distinguishing peak and off‐peak periods, spatial analyses are conducted from the perspectives of accessibility differences across ring roads, hotspot–coldspot clustering, and supply–demand matching. Areas in urgent need of accessibility improvement are mainly concentrated between the first and third ring roads. A street‐level equity analysis further reveals that peak periods significantly exacerbate inequality in park accessibility. Moreover, multi‐scale geographically weighted regression (MGWR) is employed to explore the spatiotemporal heterogeneity of accessibility determinants, demonstrating that road network density consistently exerts a positive effect, whereas limited public transport accessibility constrains improvements in park accessibility. Finally, policy‐oriented recommendations are proposed from the perspectives of central urban areas, modal shift, and peripheral urban zones, providing scientific support for the rational allocation of park resources.\n"]