There are many reasons for facial asymmetry, which usually include the following reasons: 1. Deformities after facial tumor surgery. If the tumor is not treated with plastic surgery at the same time, various tissue defects or organ displacement will occur on the face, resulting in facial deformity. 2. Unexplained hemiatrophy. The cause of the disease is unknown, and the natural atrophy of unilateral face leads to serious facial deformity. 3. Developmental facial asymmetry. During the development period, one side of the face appears developmental retardation, until the adult appears facial asymmetry, that is, one side of the face is fuller than the other. It is divided into physiological development asymmetry deformity, which is often not very serious, usually does not need plastic surgery, and has certain heredity, and exists in many normal people; Some congenital diseases, such as hemifacial short syndrome, will lead to severe hypoplasia of one side of the face, accompanied by auricle deformity, and a series of plastic surgery must be started around 6 years old; Childhood facial trauma, isotope therapy of facial hemangioma, bad chewing habits, tooth deformity, etc. will all lead to unilateral facial development disorder, which will show facial asymmetry in adulthood. 4. Traumatic facial asymmetry. Severe trauma can lead to necrosis or scarring of subcutaneous adipose tissue of facial skin, facial bone fracture can not be reduced, and facial deformity will appear after healing. With the development of transportation industry, the disability caused by this kind of reasons has an increasing trend.