Two-year-old children with bad breath need to strengthen oral hygiene, focusing on the elimination of soft dirt and food debris, if there are digestive diseases need to improve the examination and active treatment. After children eat food, due to their relatively poor autonomy, not able to rinse their mouths and brush their teeth independently, so the food residues and some of the soft dirt in the mouth are easy to be deposited on the surface of the teeth and in the crevices. Bacteria in the mouth will break down carbohydrate foods to produce acid, and protein foods to produce ammonia and hydrogen sulfide, which is the cause of bad breath. The first thing you need to do when you notice bad breath is to clean your child’s mouth. Mouth rinsing is usually done at the end of the meal, and parents can help their two-year-olds learn how to do it if they are too young to do it on their own. Brushing is the easiest and most effective way to keep the mouth clean, parents can choose a baby-specific toothbrush, pay attention to the need to choose a small brush head, soft bristles of the toothbrush. At the same time, when brushing teeth, you should carefully clean the surface of children’s teeth and teeth gap. If the child’s bad breath is not triggered by the oral cavity, you need to pay attention to the presence of digestive diseases, such as the presence of constipation, gastrointestinal inflammation, gastrointestinal pylori infection and other conditions. In this case, it is necessary to go to the gastroenterology department in time for examination and symptomatic treatment.