Black stool in gastric ulcer indicates that gastric ulcer combined with peptic bleeding is a more serious complication. There are four most common complications of gastric ulcers: the first is peptic bleeding; the second is peptic perforation; the third is pyloric obstruction; and the fourth is cancer. Patients with gastric ulcer combined with gastrointestinal bleeding mainly manifest as black stool, and some patients are in the process of defecation in the toilet suddenly appear head confusion, dizziness, panic, sweating, and in serious cases can appear fainting, which need to go to the hospital immediately for treatment. If there is only a small amount of black stool, acid suppressants and hemostatic drugs can be applied to treat the bleeding, and most patients can stop bleeding. In case of heavy bleeding, the patient may need immediate blood transfusion and hemostatic treatment. If the transfusion is not effective, emergency surgery is needed, which is either a major gastrectomy or a crusting of the ulcerated surface or bleeding point of the ulcer. Therefore, patients with black stools must seek medical attention and treatment in a timely manner to prevent hemorrhage from occurring.