When children’s milk teeth have caries, many parents will not take it seriously, thinking that the milk teeth will be replaced sooner or later and there is no need to treat them. In fact, this is a common misunderstanding. According to the second national oral health epidemiological survey, the incidence rate of dental caries among 5-year-old children in China reached 76.55%! It turns out that the calcification degree of milk teeth is low and the acid resistance is poor, plus the children do not brush their teeth actively and love to eat sweets, so they are very easy to suffer from caries. If the milk teeth caries is not treated in time, it can bring the following harm. Affect the growth and development. The replacement of milk teeth and permanent teeth is carried out in a certain order, usually starting from about 7 years old, from incisors to molars, one by one, until about 12 years old. Thus, although the milk teeth will be replaced, they are responsible for the chewing work for 10 years during the growth and development of children, especially the 8 milk molars which have a large chewing function and are replaced most late. If a child has multiple decayed milk teeth, the chewing function will definitely be reduced, which will affect the child’s nutritional intake and the growth and development of the jaw, face and whole body. It will lead to incomplete development of permanent tooth germ. If the baby tooth caries is not treated, the caries progresses rapidly and may develop into pulpitis and apical inflammation, and the infection may develop to the permanent tooth germ below the baby tooth while the child is suffering from pain, resulting in the incomplete development of the permanent tooth enamel, or even unable to develop. It will lead to uneven tooth alignment and affect the aesthetics. If the decay of milk teeth is serious, it may lead to the premature loss of milk teeth, and the permanent teeth underneath will be affected as well, resulting in premature or late eruption, resulting in the misalignment of teeth and affecting the bite relationship. In addition, if one side of the baby tooth is severely decayed, the child will not dare to chew with the affected side and develop the habit of chewing on the side, which will lead to the asymmetric jaw development of the child and seriously affect the beauty. In addition, early childhood is the critical period for children to learn language, the large area of decay of the front teeth will affect the correct pronunciation, and also affect the aesthetics, which will affect the children’s psychology. Therefore, parents and teachers should not ignore the caries of milk teeth, and help children to develop the habit of brushing teeth in the morning and evening, and rinsing mouth after meals. And do regular check-ups, find out the dental disease timely treatment, so as not to bring adverse health effects.