Objective：To study the incidences of childhood obesity between urban and rural area in Chongqing and its related factors. Methods：According to the cluster sampling method，a total of 77 411 school-age children aged 6 to 18 years from Chongqing urban and rural area were enrolled. Height，weight and body mass index（BMI） were measured. According to the method of stratified cluster sampling，4 400 children from 2 urban schools and 3 rural schools were extracted to fill obesity influencing factors questionnaires. Children were divided into obese group and control group according to BMI，childhood obesity related multivariate Logistic regression analysis was made and differences of obesity risk factors between urban and rural were compared. Results：（1）Overall obesity inci－dences among school-age children in Chongqing were 8.23%，9.70% in urban and 5.32% in rural areas（P<0.000 1）. （2）Obesity re－lated factors logistic regression analysis demonstrated that birth weight，meat，fried food，beverage，snack intake frequency，maternal smoking and family history of obesity were risk factors for childhood obesity in urban area；breastfeeding，vegetable intake frequency and vitamin supplements were protective factors. At the same time，birth weight，fried foods，milk products，snack intake frequency，parents BMI were risk factors for childhood obesity in rural area；breastfeeding was protective factor. （3）Urban children ate more meat，fried foods and milk product than rural children；family obesity history rate was higher while breastfeeding rate was lower in urban children than in rural children（P<0.05）. Conclusions：Childhood obesity incidence of urban area is higher than that of rural area in Chongqing and the influencing factors are maternal nutrition during pregnancy，maternal smoking，feeding mode，way of life and family history of obesity. To control childhood obesity in urban，we should focus on advocating smoking cessation during pregnancy，raising breast feeding rate and controlling meat，fried food，sugary drinks，snack intake of children. Childhood obesity incidence is lower in rural area than in urban area，but the growth rate is higher in rural area than in urban area；measures should be taken to im－prove children’s dietary patterns and control fried foods，milk products and snack intake to avoid recommitting the same error of ur－ban children.