<p>Urban parks provide important places for the public to engage in physical activities. However, certain aspects of the built environment may affect residents’ physical activities in these parks, and these aspects may vary depending on the city context. Studies have not yet fully explored the factors affecting physical activities in urban parks in Chengdu, China. Furthermore, an in-depth analysis and exploration of the causes behind how the park environment affects physical activity is lacking. This study focused on five urban parks in Chengdu City. Specifically, logistic regression was applied to questionnaire data to study how the built environment of the urban parks affects the duration and frequency of residents’ physical activities. The results indicated that the built environment of the five parks has a significant effect on both duration and frequency. Specifically, the primary factors affecting the duration of physical activities include sanitation maintenance, plant landscape, the presence of a playground, site facilities, lighting facilities, and public toilet facilities. The frequency of physical activities is significantly impacted by pathway maintenance, the playground, pathway width, pathway length, site facilities, and water quality management. The study also explored the causes of how the built environment affects physical activity, proposing several design strategies. These strategies include improving the quantity and quality of the park site and facilities, designing suitable roads, maintaining the environment, and providing an attractive landscape.</p>