From the perspective of environmental justice, this study focuses on residents who choose to walk or travel by private car, and uses Gaussian-based two-step floating catchment area (2SFCA) model and Gini coefficient to measure the spatio-temporal disparity of the accessibility and equity of PGS in Wuhan's central urban area from 2000 to 2018. The non-linear influence and threshold effect of traffic factors, land use factors and socio economic factors on the accessibility of PGS are further analyzed by using the Gradient Boosted Decision Tree (GBDT) model, which is aimed at providing relevant reference for urban green space planning under the guidance of equity. The results showed that:(1) The supply and demand of PGS increased rapidly and the travel cost of residents decreased gradually during the study period; (2) The areas with high accessibility of PGS in two modes were expanded, and it was mainly distributed around the banks of the Yangtze River, lakes and large scenic areas, but the areas with low accessibility by walking were more than those of driving in different periods. Meantime, the Gini coefficient showed that residents enjoyed inequity opportunities to park green space services by walking and driving, and the degree of inequity by walking was much greater than that of driving; (3) Land use structure and socio economic factors had synergistic effects on the accessibility of PGS in different periods, and traffic factors were the main reason for the difference in accessibility between different modes; (4) The non-linear diagram showed that the threshold effect of key variables could provide a quantitative reference for the refined planning and management of urban green space.