Abstract: Taking Shanghai's large city-ring parks as the study object, this paper evaluates their recreational-service utility by combining utility theory with big-data analysis. First, the off-season and peak-season performance of the sample parks is assessed along three dimensions: service intensity, service scope, and service attributes. Second, differences in utility are explained through a comparative analysis of the parks' internal and external characteristics, including functional distinctiveness and diversity, the appeal of themed events, transport accessibility, location, and the types of adjacent communities. The paper then derives planning implications and proposes strategies for improving the quality and performance of large city-ring parks. These include tailoring improvement measures to each park's development stage and service potential; determining spatial structure, themed programming, and facility provision according to functional positioning; and coordinating the planning and construction of urban park-and-green-space systems with road and transport systems.