Objective: To systematically review the associations of physical activity (PA), sedentary behavior (SB) and sleep with obesity, as well as isotemporal substitution effects among behaviors, determined with compositional data analysis methods, to provide a reference for obesity interventions among children and adolescents. Methods: Studies in the CNKI, Wanfang, PubMed, SPORTDiscus, Web of Science and Medline databases were searched from January 1, 2014 to May 1, 2022. Two experienced reviewers independently completed document screening, data extraction and quality assessment. Results: Sixteen articles were included, with a methodological quality score range of 7-12 points. Moderate to vigorous physical activity (MVPA), sleep and obesity were negatively correlated, and substituting other behaviors with MVPA decreased obesity risk. The substitution time ranged from 1.5 min/day to 60 min/day. Light physical activity(LPA) and SB were positively correlated with obesity. Conclusion MVPA is the primary focus of obesity interventions in children and adolescents, and extra 60 min of MVPA per week on the existing level of physical activity may be the minimum necessary to decrease the risk of obesity.