Three-year-old babies get up in the morning with bad breath, mostly considered to be inattention to oral hygiene, indigestion, inflammatory diseases, Helicobacter pylori infection and other causes, need to go to the hospital, clear causes and then treatment. 1, poor oral hygiene: three-year-old babies have not developed a good habit of brushing their teeth before bedtime, in the morning, rinsing their mouths before and after meals, coupled with the slower flow of saliva at bedtime, which is conducive to the breeding of bacteria, appearing in the morning Bad breath. Parents are advised to urge their babies to carry out daily oral cleaning care and drink more water; 2, indigestion: eating too much or consuming too much indigestible, sweet and greasy food, resulting in indigestion, food residues remain in the stomach, intestines, and even the mouth, fermentation for a long time to produce an unpleasant taste and the formation of bad breath. It is recommended to eat a light diet, eat more fresh vegetables and fruits, eat less sweet and fatty, stimulating food, and if necessary, follow the doctor’s instructions to be given stomach and appetite tablets, probiotics; 3, oral diseases: such as chronic gingivitis, oral ulcers and other diseases, but also easy to cause bad breath. It is recommended that timely medical treatment, follow medical advice, gingivitis available compound chlorhexidine mouthwash; baby mouth ulcers can apply watermelon cream for treatment, along with taking vitamin C to assist in the treatment; 4, H. pylori infection: H. pylori can decompose urea to produce a substance with a special odor – ammonia, coupled with the pylorus Helicobacter pylori infection can damage the gastrointestinal digestion and absorption function, resulting in the retention of food residues in the gastrointestinal, can cause bad breath. The patient needs to be treated with quadruple therapy to eradicate it, and also pay attention to eating at separate tables during treatment. Three year old babies with bad breath in the morning, parents must train their babies to develop a good habit of brushing their teeth before bedtime and in the morning, usually drink more water and pay attention to oral hygiene.