Objective: To explore the impact of teacher student relationship and peer relationship on externalizing behaviors among migrant children, and to investigate the mediating role of school attitude. Methods: A longitudinal follow up study was designed among 378 migrant children from Hubei, Guizhou and Chongqing city with the teacher student relationship, peer relationship questionnaire, school attitude and the externalizing behavior collected through questionnaire survey. Results: After controlling covariates and baseline (T1) externalized problem behaviors, baseline (T1) teacher student relationship and peer relationship negatively predicted externalizing behavior at T3 ( β teacher student =-0.12, P =0.08; β classmate =-0.20, P <0.01), The mediating effect of school attitude at T2 on the association between externalizing behaviors with teacherstudent relationship (-0.11) and peer relationship(-0.05). Conclusion Teacher student relationship and peer relationship affect externalizing behaviors among migrant children through school attitude. High quality teacher student relationship and peer relationship might help to reduce externalizing behaviors among migrant children.