Malocclusion refers to a variety of deformities caused by the misalignment of the teeth in relation to the jaws and the craniofacial region. Commonly, there are crowding of teeth, sparse teeth, anticlockwise, open, deviated jaws and so on. If the malocclusion is not corrected in time, it will bring many harmful effects to the patients. Local harm: 1, affecting the development of the jaw. In the process of children’s growth and development, due to malocclusion will affect the normal development of the soft and hard tissues of the maxillofacial area. If the anterior teeth are not treated in time, the lower dental arch limits the development of the premaxilla, and the lower jaw is not limited by the maxillary teeth and excessive forward development, which forms the depression of the middle 1/3 of the face and the mandibular anterior protrusion deformity, along with the seriousness of the malocclusion, the face is gradually presented with crescent-shaped face, commonly known as the face of the pig’s waist. One side of the back teeth anti-collision or misalignment can cause facial development asymmetry. 2, affect oral health. Misaligned teeth crowded misalignment is not easy to self-cleaning and good caries and gingival, periodontal inflammation, and often due to misalignment of teeth and occlusal trauma. 3, affect oral function. Severe malocclusion can affect the normal function of the oral cavity, such as the front teeth open and close easy to cause abnormal pronunciation; posterior teeth locking can affect the chewing function; mandibular protrusion is easy to cause swallowing abnormalities; mandibular retraction affects the normal respiration, and in severe cases can cause sleep apnea syndrome. 4.Impact the appearance of appearance. All kinds of malocclusion can affect the appearance of the face, can show open lips and teeth, double jaw protrusion, long face or short face and other facial deformities. Systemic hazards: malocclusion not only causes harm to the localization of teeth and jaws and craniofacial area, but also to the whole body, such as indigestion and gastrointestinal diseases caused by reduced mastication, and affecting the respiratory function of the brain leading to long-term oxygen deprivation, which affects the normal development of the brain, etc. In addition, due to the malocclusion of the face and mouth, it can affect the normal development of the brain. In addition, the deformity of the face can cause serious psychological and mental disorders to the patients.