Abstract: Objective:To investigate of the early pubertal development,aggressive behavior,self-esteem and parent-child attachment of middle school girl,explore the mechanism of pubertal development and aggressive behavior,and reveal the intermediary role of self-esteem and parent-child attachment in the early pubertal timing and aggressive behavior of girls.Method:The pubertal development,aggressive behavior,self-esteem and parent-child attachment of 1130 middle school girls were investigated by questionnaire.Results:The scores of self-esteem and parent-child attachment in middle school girls were higher than those in high school girls(P0.01),the score of pubertal development in high school girls was higher than that in middle school girls(P0.05).The early pubertal timing was positively related to aggressive behavior(P0.01),and negatively related to self-esteem and parent-child attachment(P0.05 and P0.01).The self-esteem and parent-child attachment played partly mediator effects between early pubertal timing and aggressive behavior,the effects of which were 33.87% and 25.98%,respectively.The early pubertal timing,self-esteem and parent-child attachment played directly effects on aggressive behavior,and the early pubertal timing played indirectly effects on aggressive behavior by self-esteem and parent-child attachment.Conclusion:For preventing the aggressive behavior of middle school girls,correct guiding,grasping self-esteem and impoving parent-child attachment can relieve and reduce the aggressive behavior of middle school girls with the early pubertal timing.