The first clinical manifestation and the first symptom of gastrointestinal bleeding is anemia and syncope: generally, bleeding volume within 400 ml can be asymptomatic, but bleeding volume greater than 400 ml can cause anemia, dizziness, general weakness, and even sudden fainting when standing up, and there are even symptoms such as cold feeling of limbs and low blood pressure. In case of massive bleeding, shock can be produced, which is manifested as agitation or confusion, cyanosis of lips and mouth, difficulty in breathing, and unmeasured blood pressure, which can lead to death if not treated in time. Next is vomiting blood or black stool. Recognizing whether it is vomiting blood or black stool depends on the site of bleeding, when there is vomiting blood, it indicates that the bleeding site is above the pylorus, if there is black stool, it means that the bleeding site is below the pylorus. Gastrointestinal bleeding can also cause azotemia, and when the bleeding volume reaches 1500-2500 ml, it can produce symptoms of shock, manifested as pallor, wet and cold extremities, cyanosis of the lips, reduced pulse pressure difference, fast and weak pulse and other signs. Therefore, gastrointestinal bleeding can cause systemic or local symptoms. When patients have black slate oil-like stools, it is recommended to go to the hospital for relevant examinations in time to exclude the possibility of bleeding.