Clinical studies have found that colonic ulcers have a certain probability of becoming cancerous, but not always form colon cancer, so it is impossible to determine the timing. Colonic ulcer is an inflammation of the mucosa and submucosa of the colon, often manifested as bloody diarrhea, mucus and blood stools or abdominal pain. The disease usually has a long duration and tends to recur, and some of them can be prolonged for several years or more than 10 years. Usually, the symptoms of colonic ulcer will be relieved gradually after active medication, together with daily diet and emotional regulation. The chance of colon ulcer becoming cancerous is 2.5-4 times higher than that of normal people, and it is mostly seen in patients with a disease duration of more than 10 years. Therefore, once a colon ulcer is diagnosed, it should be treated actively, and regular review and colonoscopy should be paid attention to, and if malignant tendency is suspected, biopsy should be performed in time for early treatment.