Objective: This study aims to investigate the menarcheal age of female junior middle school students in Tianjin and associated factors, providing suggestions for further development of adolescence education on physiological and mental health. Methods: A total of 4 127 junior middle school girls in Tianjin area were selected by stratified random sampling method, and investigated by the method of physical examination and questionnaire survey, results were analyzed. Results: There were 1 383 girls reported menarche. Mean age at menarche was(12.68±1.19) years old; One-way ANOVA showed that girls with higher family income, higher parental education had earlier menarcheal age(F=4.97, 9.52, 10.64, P<0.05). It showed that the tendency that obesity group and over-weight group was higher in the rate of menarche than that of normal group and marasmus group(F=4.20, P<0.05). However, different time on watching TV, computer or celephone and sleeping was found to be unrelated with age at menarche(P>0.05). Kruskal Wallis H test showed that girls whose mothers’ AAM was earlier had earlier menarcheal age(H=82.94, P<0.05). According to age, girls were divided into groups of 10-11, 11-12, 12-13 and 13-14 years old. Girls in each age group were divided into the menstruation menarche group and the non-menstruation menarche group. The results showed that the levels of height, weight, BMI, waist circumference, hip circumference, and the skin fold thickness in menstruation group were higher than those in non-menstruation group(t=2.18-10.93, P<0.05). After that, girls of each group were divided into four group：marasmus group, the normal group, the over-weight group and the obesity group according to BMI(χ2=34.66，13.37，11.09，12.60,P<0.05). Conclusion Female junior middle school students’ menarcheal age in Tianjin is related to family income, parents’education, mother’s age at menarche, obesity and physical exercise frequency.