A patch on the baby’s tongue is medically known as map tongue. Map tongue is a kind of chronic marginal exfoliative linguitis that occurs in the superficial layer of the tongue mucosa, the cause of which is still unclear, the main factors are genetic factors, immune factors, psychosomatic factors, endocrine factors, nutritional status, oral local environment, etc.. Map tongue can be prevented by active measures, such as avoiding emotional stress and strain, reducing mood swings, actively treating systemic diseases or lesions in the mouth, paying attention to hygiene and maintaining good digestive function. The main treatment is oral administration of the B vitamin niacinamide. The map tongue generally has no adverse effects on the body of children, and only requires symptomatic treatment.