Abstract: Objective:To investigate the characteristic of sagittal split ramus osteotomy（SSRO） on mandibular prognathism and its influence to the modality and function of temporomandibular joint（TMJ）.Methods:Thirty four patients with mandibular prognathism were selected and underwent after-operative orthodontics treatment,SSRO with mini-plates rigid internal fixation,postoperative elastic traction and orthodontics.Results:After one to four year following-up,well occluding were acquired after the surgery,and the symptom of TMJ disappeard or relieved.Conclusion:It is suggested that SSRO may be an effective way to correct mandibular prognathism,and the condyle should be located in the glenoid fossa to avoid the symptom of TMJ.