Indications: Severe osteogenic jaw deformity. Pre-operative preparation: 1. Visit orthodontic department of regular hospital, perform cephalometric examination and diagnosis. (1) whether it is osseous deformity or odontogenic deformity. Odontogenic malformation can be corrected by orthodontic treatment. (2) Which kind of deformity is it. (3) Whether it is a single jaw deformity or a double jaw deformity. (2) Develop a surgical plan according to the type of malformation. 3.Bone deformity: orthodontic treatment related to orthognathic surgery is needed to cooperate with the surgery. This orthodontic treatment is different from the general orthodontic treatment. Orthognathic surgery: cut open the jaw bone and refix it. Postoperative orthodontics: adjust the bite relationship to achieve the ideal bite.