Urban park green spaces (UPGS) are essential resources for improving the urban ecological environment and meeting residents’ recreational needs. However, during rapid urbanization, the layout of UPGS often exhibits spatial inequity, with significant differences in the resources enjoyed by resident groups with different socioeconomic attributes. Accurately assessing the spatial equity of the UPGS layout (the equal accessibility of UPGS) is crucial for optimizing resource allocation and promoting social equity. This study takes the main urban area of Nanjing as an example and utilizes location-based service (LBS) data and multi-source geographic data to conduct an in-depth characterization of residents’ socioeconomic attributes, recreational behaviors, and park green space layout at the street scale. By constructing indicators of resident heterogeneity and UPGS supply–demand matching degree, it reveals the differences in park green space accessibility among different social groups and locations and explores the correlation between resident heterogeneity and UPGS spatial equity. The study finds that the layout of UPGS in the main urban area of Nanjing exhibits significant spatial inequity, with generally poor accessibility to park green spaces in the central urban area and low-income communities. The higher degree of diversification of residents’ socioeconomic attributes leads to a lower level of UPGS spatial equity in their streets. The results of the big data analysis verify the significant impact of resident heterogeneity on the equity of park green space layout. This study reveals the spatial equity issues of UPGS layout from the perspective of resident heterogeneity, providing new ideas and evidence for optimizing the allocation of park green space resources. Future UPGS planning should pay more attention to the diversity of residents’ recreational needs, focus on improving the accessibility of park green spaces in central urban areas and low-income communities, and balance the interests and demands of different stakeholders through public participation mechanisms.
