Gastric ulcer has a certain chance to turn into gastric cancer. Gastric ulcer belongs to a benign disease, but it is mostly considered as precancerous lesion of gastric cancer in clinical practice. Patients with long-term gastric ulcer have about 1% chance to develop malignancy and form gastric cancer, especially huge ulcer with diameter greater than 2cm, which should be distinguished from malignant ulcer. In general, if a patient is above 45 years old and has a history of long-term gastric ulcer, if the ulcer has recently caused a change in the pattern of gastric pain, that is, a vague pain in the upper abdomen, burning-like or dull pain, starts within 1-2 hours after meals, and then slowly and gradually decreases. Now, the pain becomes irregular and persistent. If the drugs that used to be effective in relieving stomach pain are not effective or even ineffective, you should be alert to the possibility of ulcer malignant precursors and go to the hospital for examination as soon as possible to clarify the diagnosis.