If a child has bad breath in the mouth, it may be caused by tooth decay or gingivitis. Because of the poor autonomy of children, and many babies have the bad habit of eating before bed, it is easy to cause tooth decay in the mouth, and the increase of bacteria in the mouth, so that bad breath appears. Once children have the symptoms of bad breath, they should go to the hospital in time to check the teeth in the mouth. For the caries of milk teeth, timely filling treatment should be carried out, because the caries of milk teeth progresses very fast and the foci of infection will progress down the roots of teeth, affecting the development of permanent teeth below and causing irreversible damage; many parents think that milk teeth have to be replaced sooner or later and do not carry out treatment in time, which leads to the malformation of permanent teeth and causes adverse effects on the oral health of the children in their life. For children’s oral diseases, prevention should be the main focus. Parents should do a good job in the prevention of children’s milk teeth caries, according to the advice of children’s dental experts, the baby should start brushing and oral cleaning as soon as the baby grows up, and after the baby grows up to the age of being able to brush teeth by himself, parents should not only urge the baby to develop the good habit of brushing teeth, but also check the baby’s oral hygiene condition from time to time to find the poorly cleaned parts and the occurrence of dental caries.