Urban green space (UGS) is essential for improving urban resilience and the well-being of residents, and UGS supply is an important aspect of the construction of eco-cities in China. As a quasi-public goods, compared to UGS equity studies within a city, there has been little research on UGS equity among different cities. This paper first established a conceptual framework for UGS provisioning of local governments, and then, based on multi-source data, the UGS equity among 58 major cities in China and the related influencing factors were investigated; lastly, strategies for making improvements were put forward. The findings showed that the proposed integrated conceptual framework could reveal the formational processes of current UGS in China’s cities, providing a coherent framework for UGS supply improvement. The average UGS of 58 cities was found to be in undersupply compared to current standards, and its spatial equity was not good; climate, urban topography, proportion of secondary industry, and title incentive factors exerted significant effects on UGS coverage, per capita UGS and accessible UGS; furthermore, the per capita gross domestic product (GDP) and land availability were found to have a significant influence on UGS coverage and per capita UGS; while population density only impacted the per capita UGS. Comprehensive governance strategies including policy innovations for the central government, capacity enhancements of local governments, UGS planning refinements in terms of contents, procedures, and standards, and the engagement of non-profit organizations should be implemented to strengthen the supply of UGS and alleviate intercity inequity.