After a child develops a mouth ulcer, parents should pay attention to the child’s oral hygiene, brush the teeth and rinse the mouth carefully, and if necessary, under the guidance of a doctor, rinse with compound chlorhexidine gargle, etc. If the pain of mouth ulcers is obvious and appetite is reduced, local lidocaine gel can be used to relieve pain, and topical ice borax, watermelon cream, recombinant human epidermal growth factor gel can also be used to promote the healing of ulcers. If your child has recurrent ulcers, or if the symptoms are heavy and do not heal easily, it is recommended to actively seek medical examination. Pay attention to a balanced diet, eat more vegetables and fruits rich in vitamins as well as minerals, get more rest and ensure your child’s sleep quality. Brush teeth and rinse mouth carefully to maintain good oral hygiene, and exercise properly to enhance immunity, etc., so as to actively prevent the disease in terms of its causes.