Abstract: Objective To investigate the prevalence and risk factors of overweight and obesity among primary and middle school students in Beijing from 2010 to 2011.Methods A total of 2 261 primary and middle school students aged 11-18 years were selected using population-based stratified cluster sampling from Xicheng district of Beijing and surveyed with a standardized questionnaire and physical examination.Logistic regression was used to analyze major risk factors.Results The overall prevalence rate of obesity among the students was 7.6%(8.2%in females and 6.9%in males).There were 74.9%of the obese students having physical exercise less than 60 minutes per day and the ratio was significantly higher than that of normal weight students(38.7%)(P<0.001).The prevalence rate of obesity was 53.8%among the students with familial history of obesity.Logistic regression analyses showed that female,spending much more time on computer use,irregular physical exercise,and family history of obesity were independently related to overweight and obesity.Conclusion The prevalence overweight and obesity is associated with a variety of factors,including genitic history and unhealthy life styles among primary and middle school students in Xicheng district of Beijing.