Children’s health and their outdoor activities are closely related. With the increasing problem of childhood obesity and the improvement of people’s health consciousness, urban planning and spatial design are required to promote children’s outdoor activities. Selecting children and teenagers of 6-18 years old in Shanghai as the object, this paper conducts a network questionnaire survey to study the status quo of their health and outdoor activities, and quantitatively analyzes the spatialtemporal characteristics. Results show that children have a high incidence of obesity and are lack of outdoor activities. The time of outdoor activities is concentrated in the daytime of weekends, and the activity venue is concentrated in the green lands and exercise fields in the community or the parks nearby. Environmental factors in the city have significant associations with children’s health and outdoor activities. At the city level, some parts of Shanghai can see remarkably high concentration or low concentration of children’s outdoor activities, and the frequency and time consumption of children’s vigorous activities within the Inner Ring is significantly higher than that in other rings. At the street level, curb parking, environmental harmony and civilization, neighborhood relationship, and the quality of children’s activity facilities have a significant correlation with children’s outdoor activities, especially with their activity frequency. At the micro level of exercise fields, children’s vigorous activities tend to happen with high time consumption and frequency in the vacant street space and sidewalks along the street.