Oral cancer is the first thing to be considered when oral ulcers keep getting bad. Many oral cancers manifest as ulcers with infiltrative growth, hard lumps can be touched at the base and around the ulcers, with elevated and untidy edges, depressed in the middle, granular bumps on the depressed surface, covered with necrotic tissue, generally painless or painful after stimulation, and spontaneous pain when invading nerves. Therefore, ulcers that are more than 2 weeks long need to be closely observed and always do not heal to seek medical attention for systematic examination, and if necessary, biopsies should be excised for histopathological examination, so as to achieve early detection, early diagnosis and early treatment. There are also the most common traumatic ulcers in the oral cavity, mostly caused by local mechanical stimulation of ulcers. If the stimulus is not removed, the ulcer will not be able to heal for a long time, and in the long run, it may cause cancer, so the treatment of traumatic ulcers is to remove the stimulus first. Children with ulcers in the mouth are mostly caused by bad habits, such as habitually biting the tongue, lips, cheeks and other soft tissues or stimulating the above soft tissues with fingers or foreign objects, causing the so-called self-injurious ulcers. For self-inflicted ulcers in children, it is important to correct bad habits and, if necessary, to ask a pediatrician for joint treatment.