This study conducted to explore the relationship between outdoor activity time, screen time and body weight of children. All participants, 3–6 years of age (n =  1422), from 4 kindergartens in Hangzhou City, Zhejiang Province were selected as the subjects by random cluster sampling. Weight and height were measured. Total screen time, time of outdoor play were self-reported by parents in a questionnaire. We used X² test, t-test and logistic regression analysis to analyze the data. After adjusting the influencing factors such as children's age, father's education level and screen time, the risk of overweight and obesity was 1.734 times (95% CI: 1.178-2.552) for children with outdoor activity time ≤ 2h/d, among which 2.050 times (95% CI: 1.252-3.357) for boys, 1.472 times (95% CI: 0.785-2.761) for girls. After adjusting the influencing factors such as children's age, father's education level and outdoor activity time, the risk of overweight and obesity in children whose screen time ≥ 1h/d was 1.639 times (95% CI: 1.272-2.113) that in children whose screen time was less than 1h/d, including 1.474 times (95% CI: 1.057-2.057) for boys, and 1.676 times (95% CI: 1.119-2.511) for girls. Thus, both long screen time and outdoor activity time were associated with the increases the risk of overweight and obesity.