It is the best surgical method at present. It is to use a 3 cm ~ 4 cm incision in the oral cavity to cut off the hypertrophic mandibular angle, and at the same time, it can cut off or grind off the mandibular outer plate and mandibular margin, and can cut off part of the masseter muscle. Advantages: Because there is only one intraoral incision in the whole operation, no surgical scar will be left on the body surface, and the surgical trauma is much smaller than the combined incision inside and outside the mouth, and the recovery is obviously accelerated. Because it is an oral approach, the authority of maxillofacial plastic surgery in Korea adopts a minimally invasive method to avoid the chance of damaging facial blood vessels and nerves. The technical requirements for operation are high.