Objective This paper aims to study the relationship between body fat and sexual development in Chinese girls with different waist circumference.Methods Six thousand one hundred and fifty six girls aged 6-19 were sampled.Their body weight,height,waist circumference,percentage of body fat and secondary sex characteristics were measured.All the subjects were divided into three groups:low class waist circumference,moderate class waist circumference and high class waist circumference.The menarche percentages were analyzed by using the status method.The menarche ages were analyzed by using the retrospective method.Estimates for mean age at entry into a pubertal stage and menarche were calculated by a probit analysis.Results The incidences of moderate class and high class waist circumstance were 20.94％ and 25.27％,respectively.The sexual development of the former was earlier than that of the latter.The percentages of the menarche were detected as high class＞moderate class＞low class.The menarche ages were expressed as high class＜moderate class＜low class.Conclusion A close association is found between the waist circumference and sexual development,especially the menarche age.Girls with high class waist circumference are more vulnerable to earlier menarche and excess body fat.It is important to control the occurrence of central obesity through monitoring the change of waist circumference in puberty for girls' health.