The best time for orthodontic treatment is determined by the type of malocclusion and the developmental status of the patient. Early orthodontic treatment of malocclusion in children is the prevention and treatment of early malocclusion by using various methods of oral therapy, which are directed at the etiology, mechanism and occurrence and development of malocclusion. In the early stage of malocclusion, the malocclusion is found and orthodontic treatment is carried out to prevent and interrupt the occurrence and development of malocclusion and restore the normal development of craniofacial dentition as early as possible. Early treatment of malocclusion in children can more effectively reduce the severity of malocclusion, reduce the difficulty of malocclusion treatment, and reduce the orthodontic burden of children in the permanent dentition and after adulthood; at the same time, it can also reduce the psychological barriers caused by malocclusion in children, which is conducive to the formation of a healthy personality of children. Orthodontic treatment of dental malocclusion in the milking period The main malocclusion in the milking period is anterior malocclusion, in addition to deep overlap and deep coverage, narrow upper arch and posterior malocclusion. Treatment of dental malocclusion usually starts at the age of 3 years due to the child’s cooperation. Treatment of malocclusion in mixed dentition The mixed dentition period is a transitional stage of occlusal development, and most of the malocclusions need to be treated comprehensively after the occlusion is established, i.e., in the permanent dentition. Early orthodontic treatment at this time is aimed at the malocclusion that affects the stability and perfection of the occlusion, the oral health of the child and the psychology. From a health and functional point of view, dental malocclusion that causes occlusal trauma and affects jaw bone development should be treated early. For example, single or multiple teeth rebound that may cause occlusal interference, lower anterior dentition trauma, tooth loosening, attached gingival atrophy, etc.; bad labial and lingual habits that may cause functional malocclusion and opening (such as finger sucking, lip biting, tongue stretching habits, etc.) should be intervened and blocked as early as possible at the early stage of tooth replacement; the presence of multiple teeth between the central incisors, tooth blocking, individual or most teeth missing, etc. should be seen as early as possible. Actively treat the caries, prevent the infection from causing the displacement of permanent tooth embryos and the loss of arch space. Especially for the patients with “enameled teeth”, early detection and early treatment are necessary. It is recommended to consult the dentist in time to avoid missing the opportunity. In summary, early detection of malocclusion in children aged 7-10 years and early orthodontic treatment can stop the development of malocclusion by early gap management and intervention. Patients with “buck teeth”, “small jaws” and “bunions” can be treated early to avoid further deterioration of the facial shape. Parents who are not sure when their child should be treated are advised to see a specialist once a year, starting at the age of 6, to avoid missing the best time for orthodontic treatment.