The causes of pediatric halitosis are divided into physiological and pathological, the former including dietary and oral hygiene factors, the latter including oral, nasopharyngeal, gastrointestinal and other disease factors. 1. Physiological bad breath (1) Oral hygiene: often do not brush your teeth, do not rinse your mouth after meals, food residues remain in the mouth and between the teeth, after bacterial fermentation to produce irritating gas, so there will be bad breath. (2) Diet: children who like to eat garlic, leeks, stinky tofu and other foods will have temporary bad breath after eating. 2. Pathological bad breath (1) Oral diseases: dental caries (tooth decay), pulpitis, periodontitis, dental calculus and other diseases may cause halitosis. (2) nasopharyngeal diseases: rhinitis, nasal polyps, pharyngitis, tonsillitis, tonsil stones can also cause pediatric halitosis. (3) Gastrointestinal diseases: children with dyspepsia, gastroesophageal reflux disease, gastric ulcers, Helicobacter pylori infection and other diseases have bad breath because the fermented gases in the digestive tract are discharged through the mouth. There are many causes of pediatric halitosis, parents should help their children to do a good job of oral hygiene, to rule out the physiological halitosis, to consider the causes of pathologic halitosis, parents are advised to take their children to the hospital in time to identify the cause and treatment.