OBJECTIVE To learn the prevalence of overweight and obesity of children aged 10 to 14 in Wuxi and to analyze its potential influencing factors. METHODS With a stratified cluster random sampling method, 2870 children aged 10 to 14 in three districts of Wuxi were surveyed by means of questionnaire and physical examination. RESULTS The incidence of overweight was 11.39% (Boys' was 10.03% and girls' was 1.36%) and that of obesity was 2.23% (Boys' was 1.64% and girls' was 0.59%). The incidence of overweight and obesity of boys was much higher than that of girls (P < 0.01). The result of multiple linear regression analysis indicated the influencing factors of BMI in childhood might include birth weight, BMI of father and mother and preference for fried foods. CONCLUSION The prevalence of overweight and obesity of children aged 10 to 14 in Wuxi was between the rich rural areas and small and middle-sized cities in China. To prevent overweight developing to obesity is an important measure. Birth weight, BMI of father and mother, preference for fried foods were the main factors affecting children's BMI. A comprehensive prevention and control measure of family intervention should be taken.