Orthodontics is the use of light force to induce the jaws to reshape in the direction the patient needs. Theoretically, orthodontics can be done at any age. From 12 to 15 years old is the peak of human growth and development, the permanent dentition (permanent teeth replacement is completed), also is the time period of jaw bone reshaping is relatively fast, at this time the orthodontic treatment is the most effective, the most stable effect. Therefore, most of the cases are completed in this period. The orthodontic treatment time should be advanced for those who have severe anterior protrusion of the upper jaw and severe recession of the lower jaw. The main purpose is to adjust the occlusal relationship between the upper and lower teeth through functional orthodontics. The anticlinal joint is released so that the upper jaw can grow and develop normally forward; the functionally oriented lower jaw moves forward so that the first molars form a neutral relationship (normal occlusal position). Orthodontic treatment for these two conditions is performed at the age of 8 or 9 years. Parents should not miss this opportunity. If you wait until after the permanent dentition or growth stabilization orthodontic treatment, it is quite difficult and the results are not perfect. Parents need to be reminded that 12 to 15 years old is the time when children are in secondary school, which is also a great time for children to grow physically, so plan ahead for the relationship between treatment and learning and life. After all, orthodontics is a long time and requires the child’s hard work and cooperation to complete.