Benign hypertrophy of the mandibular angle of the chewing muscle is a common facial deformity in the Oriental population. The facial shape in this group is often wind-shaped and use-shaped. The lower third of the face is significantly wider. In severe cases, the mandibular angle protrudes backward and downward, and some are accompanied by shortening of the lower third of the face. Patients have visible or palpable hypertrophic bulging chewing muscle strips when biting. Most of the cases are bilateral, but a few are unilateral. Left-right asymmetry is also common in bilateral cases, while unilateral asymmetry is very pronounced. Most patients have no significant discomfort. Clinically, chewing muscle hypertrophy is also called mandibular angle hypertrophy or benign hypertrophy of chewing muscle, clinically it is rare to remove the hypertrophy of chewing muscle alone, if the bite muscle is really hypertrophy, generally the surgery is mostly to remove the mandibular angle at the same time to remove part of the bite muscle. First of all, from the appearance, the general chewing muscle hypertrophy patients face shape is mostly near square, so there is a “four-sided face” called. The patient is asked to chew with the mouth closed while touching the bite muscles bilaterally at the angle of the jaw to feel the contraction range of the chewing muscles and the thickness of the bite muscles. In patients with chewing muscle hypertrophy, the chewing muscle can be clearly felt when contracting and the chewing muscle is significantly thickened. X-ray examination: X-ray mainly examines the hypertrophy of the mandible and mandibular angle, but the degree of development of the chewing muscle cannot be shown on X-ray. “X-rays can be taken to determine the degree of hypertrophy of the mandibular body. However, X-rays may not be used as a routine preoperative examination. Other routine preoperative examinations: routine blood test, routine urine test, chest X-ray and electrocardiogram.