Gastrointestinal bleeding is generally divided by the Treitz ligament, which divides the GI tract into upper and lower parts. Upper gastrointestinal bleeding is more commonly caused by ulcer disease, portal hypertension bleeding, and some neoplastic causes of bleeding. Among them, bleeding caused by ulcer disease accounts for 50%, and bleeding from ulcer disease is accompanied by vomiting, black stool, and even vomiting blood; moreover, the probability of haemorrhage in many patients with ulcer disease is 20-25% of those with ulcer disease, and even after the first haemorrhage has been treated to achieve hemostasis, it is more likely to occur a second or more times; the occurrence of haemorrhage from ulcer disease will make people dizzy, blood pressure Therefore, in daily life, ulcerative patients must develop good eating habits, avoid eating stimulating foods such as too sweet, too salty, too acidic, too cold, too hot, etc., and try to eat less food that strongly stimulates gastric acid secretion and drinks with strong stimulating properties. In addition, bleeding from portal hypertension accounts for 10-25% of upper gastrointestinal bleeding. If gastric bleeding is caused by gastric tumor, the symptoms associated with gastric tumor will be manifested (stomach pain, belching, emaciation, black stool, etc.). In addition to this, upper GI bleeding is usually accompanied by symptoms of bloody stools, which are usually tarry in color. Lower gastrointestinal bleeding includes the more common colonic bleeding, bleeding due to neoplastic causes, some vascular malformations, ischemic colitis, inflammatory bowel disease, colonic polyps, hemorrhoids, etc.; colonic bleeding accounts for 87%-95% of the cases. The most typical symptom of lower gastrointestinal bleeding is blood in the stool, and the color of the stool varies, from dark red stool for bleeding above the transverse colon to bright red stool for bleeding below the splenic flexure of the transverse colon. If there is severe abdominal pain before blood in stool, it indicates ischemic enteropathy; if the abdominal distension or cramping pain before stool is relieved after stool, it is related to colorectal tumor; if purulent blood in stool is accompanied by abdominal pain, urgency and fever, inflammatory bowel disease should be considered.