Towards a multi-scale modeling framework for equity evaluation of urban green space in metropolitan cities

• This study developed a comprehensive framework for evaluating the equity of UGS by integrating 4 datasets and employing 2 model-based metrics. • CCDM was constructed to assess quantitative, spatial, and social equity dimensions using 24 supply–demand indicators. • The residential-level Multi-traffic Model quantified UGS accessibility through the optimized Ga2SFCA method. • The framework is not only applicable to UGS but can also be extended to assess the equity of other public infrastructures in metropolitan cities. Urban green space (UGS) is an integral part of the urban environment. This study established a systematic framework integrating macro–micro scales to evaluate urban green space equity, addressing critical gaps in existing methodologies. Using Nanjing’s Main Districts as a case study, 2 complementary models were developed. The block-level Coupling Coordination Degree Model (CCDM) was constructed to assess quantitative, spatial, and social equity dimensions using 24 supply–demand indicators with entropy-based weighting. The residential-level Multi-traffic Accessibility Model quantified UGS accessibility through the optimized Gaussian Two-Step Floating Catchment Area (Ga2SFCA) method for walking, bicycling, driving, and metro travel modes. Key findings included: (1) Macro-scale coordination classified 37.7 % of blocks as Coordinated Development (high equity), 49.1 % as Transitional Development (moderate equity), and 13.2 % as Disorder Recession (low equity). (2) Micro-scale accessibility performance exhibited > 90 % coverage for metro but significant deficits for bicycling and driving. (3) Spatial mismatches concentrated in southwestern and northeastern peripheries. Based on the results, the research proposed corresponding optimization strategies for 3 types of blocks. The framework can provide a transferable methodology for public infrastructure equity studies, offering actionable strategies for urban renewal.