ABSTRACT: Community park is an important part of the community life circle, and their fitness facilities are an important carrier to implement the “community 15-minute fitness circle”. Taking the fitness facilities in the high-density old urban community park in Nanjing as the research object, through behavior observation and grounded theory, this paper studies the number distribution of facilities, user activity characteristics, satisfaction, and other aspects. Based on the behavior observation results, the intensity of activities carried out by people in the site is mainly high intensity, followed by low intensity, and medium intensity is the least. Different time periods, age groups, facility distribution, and spatial forms have an impact on the level of sports activities. Based on the grounded theory, this paper summarizes eight main categories that affect the use satisfaction, including science, safety, accessibility, culture, comfort, aesthetics, purpose of use, and way of use, and constructs a theoretical model of the impact factors of site use satisfaction. Based on the comprehensive analysis of the results and the requirements of urban community fitness facilities, this paper puts forward targeted suggestions for community park fitness venues to promote the level of sports public service.