Little baby bad breath is mainly due to oral local causes of symptoms, may also be due to poor lactose absorption, Helicobacter pylori infection and other symptoms caused by, should be timely consultation to identify the cause. 1. Oral localization: it is mainly due to tooth decay, gum inflammation, dental calculus, or not brushing teeth after eating, eating before going to bed immediately after going to sleep and so on, which leads to the phenomenon of bad breath in little children. 2. Poor absorption of lactose: lactose is a bimolecular sugar, to be broken down into single molecules, including glucose and galactose, under the action of lactase in the small intestine, and then absorbed, if the absorption is imperfect, to the large intestine after fermentation will produce gas, acidic small molecules, resulting in bad breath. 3. Helicobacter pylori infection: Helicobacter pylori infection is a more common factor in older children and can also cause bad breath. This symptom alone is not enough to diagnose the disease, and there are other factors that may be causing it. It is recommended that the patient should consult a doctor in time to clarify the cause of the disease and give targeted treatment.