Objective: To explore age of menarche and associated factors of Han nationality, Zhuang nationality and Yao nationality girl in Guangxi, and to provide reference for the development of adolescent health education in schools. Methods: The 7-, 10- and 13-year-old girls of Han, Zhuang, Yao nationality were chosed from three counties of Guangxi, and height, weight and other physical indicators were measured for three consecutive years, and age of menarche was inquired. 448 cases of with compete data in the three consecutive years of monitoring. The influencing factors were investigated through questionnaire. Results: Age of menarche of the whole sample was 11.83(95%CI=11.69-11.96)years old, and that of the Han, Zhuang,Yao nationality was 11.87(95%CI=11.64-12.09), 11.44(95%CI=11.25-11.64)and 12.42(95%CI=12.14-12.70)years old respectively, the difference was statistically significant(P<0.05). Height, sitting height, weight of menarche group in 12 and 13 years old were significantly higher those of the group without menarche(P<0.05). Logistic regression analysis primary sitting height,the chest circumference,intake of seafood,duration of sleep in the night and school exercise time were the primary factors for age at menarche(P<0.01). Conclusion There are ethnic differences in age of menarche among girls in Guangxi, and it is related to sleep,physical activity and dietary structure. Puberty recated health education for girls might start at the fourth grade of primary school, focusing on the education of health life patten, balanced dietary habits, regularly routine, with the goal of growth and development promotion.