The indications for blood transfusion include acute bleeding, anemia, severe trauma, abnormal coagulation function, etc., which should be carried out in accordance with medical advice. 1. Acute hemorrhage, acute hemorrhage caused by various reasons such as trauma and pathological hemorrhage is the main indication for surgical blood transfusion. Generally, when the blood loss is less than 30%, no whole blood is transfused; when it is more than 30%, half of whole blood and half of concentrated red blood cells are transfused, and then crystals and colloid fluids and plasma are used to replenish blood volume. 2. Anemia, generally when hemoglobin is less than 70g/L, blood transfusion will be considered. 3. Serious trauma or extensive burns, the need for blood transfusion, can play a role in the prevention and treatment of shock. 4. Abnormal coagulation function, such as hemophilia, thrombocytopenic purpura and other bleeding tendency, will be transfused before surgery to supplement platelets and coagulation factors, which is conducive to stop bleeding. Whether blood transfusion treatment is needed needs to be carried out under the guidance of specialists.