Compound ulcers are ulcers that occur in both the stomach and the duodenum. Compound ulcers are not precancerous, but may become cancerous if they are left untreated for a long time or if they occur repeatedly, with repeated episodes of irritation during damage repair. It is not precancerous: when the ulcer is only mucosal damage and there is no change in cell morphology and function, it will not become cancerous. When ulcers occur for a long time, the gastric mucosa and duodenal mucosa are in the process of growth and repair for a long time, and the damage repair process is stimulated by repeated episodes of stimulation, the mucosal cells are in the state of active growth and division, and if no intervention and treatment are carried out, there is a possibility of tissue lesions. Cells in the retention of the original physiological function on the basis of some morphological and functional changes, at this time known as precancerous lesions. Therefore, when compound ulcers occur, it is recommended to carry out endoscopy and pathological tissue biopsy in time to determine the condition and intervene early according to the results without delay, so as not to miss the treatment.