Blood transfusion is an important clinical method for correcting anemia, replenishing blood volume, and improving shock status. However, given that blood transfusion carries certain risks, clinical blood transfusion is quite cautious and careful. There are the following precautions: 1. homotypic transfusion, including Rh blood type and ABO blood type; 2. component transfusion, advocating the supplementation of component blood, such as suspended red blood cells, plasma, platelets, etc.; 3. pay attention to the speed of transfusion; 4. before and after the transfusion, the patient’s vital signs should be strictly observed; 5. before the transfusion, check the pre-transfusion nine items, including the test of hepatitis B two-half pairs, syphilis, AIDS and so on.