Abstract: Objective To describe sleep duration and sleep quality and its relations with obesity among adolescents in Ningbo,and to provide basis for prevention and control of overweight and obesity among middle school students.Methods A multistage stratified random sampling method was used to investigate health-risk behaviors in 7-12 grades among middle school students.A questionnaire survey included general demographic information,sleep quality,physical activity,as well as physical examination was conducted.Results The prevalence rate of overweight/obesity among the middle school students in Ningbo was 15.35%,of which 20.97% for boys and 9.95% for girls.The rate of sleep insufficiency (8 h/d) was 48.11%,42.78% for boys and 53.24% for girls.Multiple regression analysis showed that the sleep duration was negatively correlated with BMI;Logistic regression analysis showed that sleep insufficiency (8 h/d) was a risk factor of overweight/obesity (OR=1.22,95%CI=1.03-1.46) for boys.Conclusion Sleep duration was associated with BMI,and insufficiently sleep may be a risk factor for overweight / obesity among adolescents,especially for boys.