Abstract: Objective:To investigate the effects of the modified sagittal split ramas osteotomy in treatment of mandibular deviation.Methods:Six mandibular deviation cases were included in this study,there were 3 cases with simply deformity,2 cases with protrusion and partial jaw deformity and 1 case with partial secondary jaw malformation.SNA,SNB and ANB by X-ray cephalometric measurement were 79-83,80-88 and-52 ,respectively.All patients were operated with the modified sagittal split ramas osteotomy combined with preoperative and postoperative orthodontic treatment.Results:Wound healing had no serious complications and the relations of the upper and lower tooth jaw and facial morphology were good.Conclusions:Treatment of mandibular deviation with the modified sagittal split ramas osteotomy combined with orthodontic treatment is a effective way,which is worthy of being widely applied in clinic.