Some children often have “rotten corners of the mouth”, some manifesting as flushing, cracking, erosion, crusting, and flaking of the corners of the mouth, which is called stomatitis. Some show small blisters at the junction of the skin and mucous membrane in the corners of the mouth, clusters of distribution, followed by erosion, oozing, local pain, may be accompanied by fever and swollen submandibular lymph nodes and (or) cervical lymph nodes, which is called herpes cornealis, belong to different diseases. Stomatitis is mainly related to B vitamin deficiency, infection and other factors. In the dry spring and winter, babies love to lick their lips resulting in dry and cracked corners of the mouth; then children with finger sucking and pencil biting are prone to corns. The treatment of vitamin B deficiency keratitis is mainly to supplement riboflavin and prevent secondary infection; drink more water, eat a balanced diet and correct bad habits. Coccidioidomycosis: After local cleaning, apply antibiotics (such as erythromycin ointment) and, if necessary, take oral broad-spectrum antibiotics. Fungal keratitis: after local cleaning, apply topical fungal control drugs, etc. Herpes orofacialis is caused by the infection of herpes simplex virus in the child. After the initial infection, the body usually produces antibodies, but the virus may still be latent in the body, hidden in the sensory ganglion cells, and will recur when the body’s immunity decreases, such as fatigue, weakness, cold and illness. In general, herpes can heal on its own, but in more serious cases, children need to be treated with antiviral drugs under the guidance of a doctor. In summary, there are many reasons for rotten corners of the mouth, the causes are different, the treatment is not the same, so it is best to find children rotten corners of the mouth in time to seek medical attention, the doctor will be the cause of treatment, so as not to delay the disease.