This paper describes the nationwide prevalence of childhood overweight/obesity in Chinese urban population. Data sets of boys and girls aged 7–18 yrs were collected from the series of Chinese national surveillance on students' constitution and health between 1985 and 2000 were divided into five socioeconomic groups, while WGOC BMI-reference was used as definitions of overweight and obesity. In 2000, the prevalence of childhood obesity/overweight in the coastal big cities, followed by that of the coastal middle/small cities, had reached the average level of the developed countries. The prevalence of obesity was low in most of the inland cities at an early stage of epidemic overweight. The epidemic manifested a gradient distribution in groups, which was closely related to socioeconomic status of the populations. A dramatic and steady increasing trend was witnessed among all sex-age subgroups in these urban groups, and the increments in obesity/overweight are exceptionally high in recent 5 years, and the prospect of epidemic obesity in China is in no way optimistic. Preventive program should be focused on the improvement of the balance between caloric intake and energy expenditure, and interventions aimed at changing children's life styles.