The social perspective of analysing the performances of ecosystems emphasises both the sides of supply and demand. The distribution of urban parks potentially affects the equity and effectiveness of a society while they provide public services for the city. Thus, urban parks can be considered as social resources with spatial attributes. This study focused on the spatial distribution patterns of both urban parks and citizens (or users) and proposes a research framework of ecosystem supply-demand relations based on social equity and justice. We evaluated the supply capacities of social services provided by the distribution of urban parks from three aspects, namely, place-based equality, social equity, and social justice, based on which supply-demand matching relations can be established with the consideration of users' demands. We proposed six indexes based on social equity and justice in order to represent the supply-demand situations of urban parks and selected the Xuhui District of Shanghai as a case study. The results showed that (1) there was a spatial inequality based on supply-demand relations of urban parks in Xuhui, particularly pocket parks; (2) the distribution of urban parks in Xuhui had equal quality, resulting in a better place-based equality; (3) social equity was inadequate because the level of shared urban parks per head needs to be improved; and (4) from the perspective of social justice, the previous consideration of urban park distributions did not emphasise the importance of the needs of the elders, the young, and children. Each unit showed remarkable differences, and units with higher densities of these two groups of people were lower than the average, which means that social justice needs to be improved. The study explored the possibility of the equal, effective, and sustainable development of a society through a careful consideration of urban park distributions.