In the child’s teething, tooth replacement, many parents are worried about the child’s teeth grow out of alignment, once the child’s teeth do not grow well to do orthodontics, spend money, not to mention that the child has to suffer a lot. Malocclusion is a developmental malformation, the cause is more complex, generally caused by genetic factors and environmental factors. According to survey statistics, 60%-70% of the misalignment is caused by acquired environmental factors, so some misalignment can be prevented, the main should do the following: 1, pay attention to the feeding of infants and young children. It is very important for infants and young children to be fed reasonably and to adopt the correct feeding posture. Advocate breastfeeding, artificial feeding, it is best to use a pacifier similar to the mother’s nipple, the opening of the pacifier is not too large, the diameter of 1-2 mm is appropriate. When artificial feeding, attention should be paid to the position of the bottle and the feeding posture to prevent the infant’s jaw from being under-extended or over-extended. After children are able to chew food, they should eat slightly hard, easily digestible food to exercise the chewing muscles and promote the development of the chewing organs. Eating foods with a certain degree of hardness can increase chewing function and promote the development of the dental and jaw surfaces. 2. Pay attention to the physical and mental health of young children, strengthen nutrition and pay attention to oral hygiene. Timely detection and treatment of systemic diseases, such as rickets, indigestion, endocrine disorders and chronic inflammation of the nasopharynx, etc. Oral diseases should also be treated as early as possible: early filling of caries, timely extraction of unlossed retained milk teeth, etc. 3.Correct the bad habits of infants and children. The first thing is to remove the cause of bad habits. For the bad habits that occur soon and last for a short time, it is not difficult to correct them through parents’ guidance, reminding and patient persuasion. If necessary, use a variety of bad habit busters to help children overcome bad habits. 4.Eugenically address the misalignment caused by genetics. Paying attention to the nutritional care of the mother and preventing maternal diseases are prerequisites to ensure the normal development of the fetus. When the fetus is born, prevent trauma during delivery. Different malocclusions have different optimal orthodontic treatment periods, which can be consulted with a professional orthodontist. Early treatment is required for malocclusions that may affect jaw development (e.g., retrognathism and poor oral habits). The treatment of milk teeth retrusion is usually started when the patient is 3-4 years old with a movable aligner and can usually be corrected in 3-6 months, but some patients will relapse during the period of tooth replacement or early permanent teeth and need to be closely observed. Bad oral habits such as lower lip sucking, nail biting, thumb eating, etc. need to be interrupted as soon as they are detected. In the period of tooth replacement, such as retrusion, jaw recession, bad oral habits, etc. should be treated early, rather than waiting until all teeth are replaced. Most malocclusions can be corrected in the early permanent dentition, usually around 11-13 years old for girls and 12-15 years old for boys. This is the basic establishment of permanent teeth, craniofacial still have some potential, good metabolic function, the most significant effect of tooth movement, so this period is the “golden period” of orthodontic treatment. For serious bony malocclusion, it is necessary to wait until the full development of maturity (about 18-20 years old) for orthognathic surgery to achieve satisfactory results.