Abstract: Objective: To explore the spatiotemporal behavior characteristics of the built environment and outdoor physical activities among older adults from a spatiotemporal perspective, and provides a new approach to promote physical activity levels among older adults and address the aging trend. Methods: Spatiotemporal behavior data of 126 older adults were collected using global position system and accelerometer. Environmental exposure data were correlated with physical activity data using spatial algorithms, and then the characteristics of travel modes, travel times, travel frequencies, and buffers were summarized. Results: 1) Six typical spatialtemporal patterns were found in outdoor physical activities of the elderly, i.e., 'point-line' type, 'migratory bird' type, 'chain' type,'free' type, 'neighborhood' type, and 'integrated' type; 2) the outdoor physical activity range in older adults was approximately 500meters around their home; 3) about 45% of calorie consumption and moderate-to-vigorous physical activity in older adults were occur in outdoor spaces, and their interests were focus on leisure and entertainment, shopping, and exercise; 4) the outdoor physical activity in older adults was characterized by high activity frequency and short duration. The activity frequency has a significant impact on physical activity levels, with an increase of one event associated with a increased 20.5 min/wk in outdoor physical activity. Conclusions: Outdoor physical activity among the elderly in China exhibits diverse spatiotemporal patterns, it is suggested that the increase of activity frequency can be considered an strategy in enhancing physical activity levels among older adults.