Malocclusion, also known as malocclusion, is a deformity between the teeth, jaws, and craniofacial area caused by genetics, disease, impaired tooth replacement, and early loss of milk teeth in children during the growth and developmental stages. The correction of malocclusion at the right time can do twice the work with half the effort. The age at which malocclusion should be corrected depends on the type of malocclusion. Mismatch orthodontic time one: the molar stage (4-5 years old) This period is mainly applicable to the molar retrusion (enamel), early orthodontic treatment is conducive to the development of the upper jaw and the prevention of permanent teeth retrusion. If the child has bad habits such as tongue extension and lip biting, they can be corrected at this stage to prevent the occurrence of malocclusion. Mismatch orthodontic correction time II: Teething stage (girls: 8-10 years old, boys: 9-12 years old) In the teething stage, if the child is found to have bad habits such as lip biting, tongue extension, forward jaw extension, as well as abnormal facial shape and abnormal tooth alignment, he/she should go to the hospital for orthodontic examination to determine whether it is a dental, functional or bony malocclusion and to clarify the treatment plan. Mismatch orthodontic time three: permanent dentition stage (girls: 11-14 years old, boys: 13-15 years old) At this time, the child’s teeth have been replaced, the bone is basically set, the general common misshapen jaw can be well treated in this stage. If the above time are missed, orthodontics can still achieve more desirable results, but the orthodontic method may be some limitations, orthodontic time will be longer, but as long as the patient’s periodontal conditions are healthy, the body is nothing systemic diseases can be orthodontic. The orthodontist reminded that in order to reduce the occurrence of malocclusion, parents should pay attention to the child’s diet, oral habits and other issues, such as: usually pay attention to eat more coarse food, if the child has finger sucking, lip biting, tongue spitting and other bad habits, to correct in a timely manner.