Objective: To explore the differences of parent-child attachment style, peer relationship, bullying behavior in gender, grade and other demographic variables, and to further analyze the relationship among parent-child attachment, peer relationship and bullying behavior. Methods: the parent-child attachment scale, peer relationship questionnaire and Olweus child-bullying questionnaire were used to investigate 532 primary school children of senior grade. Results: the gender and grade of parent-child attachment had significant differences in total score, and the gender of parent-child attachment also had significant differences in intimacy tendency and trust degree. There are significant differences in gender and grade of bullying behaviors in all dimensions, and boys score significantly higher than girls in all dimensions of bullying behaviors. The gender difference in peer acceptance was significant, but there was no grade difference. The two dimensions of parent-child attachment are significantly positively correlated with the dimension of peer acceptance and the dimension of peer fear and inferiority, respectively. The two dimensions of peer acceptance and parent-child attachment in peer relationship are negatively correlated with the three dimensions of bullying behavior while the three dimensions of peer fear and inferiority in peer relationship are positively correlated with the three dimensions of bullying behavior. Conclusion: the level of parent-child attachment between parents and children can significantly predict bullying behaviors in school. Peer relationship plays a part of mediating role between parent-child attachment and bullying behavior.