Gastrointestinal bleeding is subdivided into upper and lower gastrointestinal bleeding, which is divided by the duodenal suspensory ligament. The common causes of GI bleeding include peptic ulcers, acute gastric mucosal lesions or ruptured esophagogastric fundic varices, and tumors of the GI tract, with different clinical symptoms and manifestations depending on the amount of bleeding. If the amount of bleeding is less than 5-10 ml, the patient undergoes laboratory tests and the stool routine occult blood test is positive. While the bleeding amount reaches 50ml per day, it will be manifested as obvious black, tarry stools. When the acute blood loss or bleeding is greater than 400ml in a short period of time, the patient will show a drop in blood pressure, and there will also be blood in the stool, vomiting blood, and in severe cases, there will be massive blood loss and induced hemorrhagic shock, which is life-threatening.