Children’s mouth ulcers need moderate supplementation of vitamin C and vitamin B complex, at the same time, should promptly seek medical attention in order to clarify the causes of mouth ulcers, standardized treatment. There are many reasons for the appearance of mouth ulcers in children, and the reasons for their appearance in medicine are still unclear, which may be caused by endocrine changes, heredity, food allergies, infections, immune factors and other reasons, and the child can supplement the appropriate amount of vitamin C and vitamin B complex, which can improve the child’s self-healing ability. Vitamin C and vitamin B complex can keep the metabolic function of human epithelial tissue in a normal state, which can effectively promote the healing of human disease injury. Children can moderate supplementation of vitamin B₁, vitamin B₂, vitamin B₅, vitamin B₁₂, vitamin C and other water-soluble vitamins, all of which have coenzyme components and play a relatively important role in the metabolic function of the child’s body. Therefore, children’s mouth ulcers need moderate supplementation of vitamin C and vitamin B complex to improve the child’s self-healing ability, but need to be used under the guidance of a doctor.