Malocclusion is often regarded as “natural” and not paid attention to, especially the malocclusion of the milk teeth, but it is mistakenly thought that “it will be fine after the permanent teeth are replaced”, in fact, malocclusion can be caused by local disorders in the milk teeth and the teeth replacement period, oral It includes not only the misalignment and misalignment of teeth, but also the misalignment of upper and lower jaws and craniofacial relationship, such as the misalignment of cuspids, crowded teeth, and abnormal development of upper and lower jaws. The occurrence of malocclusion can be avoided by taking some preventive measures before the occurrence of malocclusion and removing various factors that may cause malocclusion. For example, it is better to breastfeed the child after birth. For artificial feeding, attention should be paid to the posture of carrying the baby, the position of the bottle, the shape of the artificial nipple and the size of the piercing. If children have bad habits such as finger sucking, lip biting, biting, cheek sucking, tongue spitting, tooth licking, mouth breathing, lateral chewing, etc., they should be educated not to develop this action that hinders the normal growth and development of the teeth and jaws, and be reminded to correct it as early as possible. If not corrected for a long period of time, malocclusion may develop, resulting in malocclusion such as labial displacement, anticuspid, maxillary protrusion or mandibular recession. If all malocclusions can be prevented at the right time, about 20% of the malocclusions can be effectively interrupted. Early detection of malocclusion should be promptly treated clinically, as children are in the growth phase and have active bone growth, so the treatment is more effective. If the labial muscle function is insufficient and the upper incisors are protruding, the labial muscle training should be strengthened; patients with receding mandibular position can be treated with functional orthodontic appliances and early training of the external pterygoid muscle to promote the forward growth and development of the mandible.