Blood warming refers to the warming of blood products in a blood warmer, or by other means, to reach a certain temperature before transfusion to the patient. Blood warming can effectively prevent large amounts of cryogenic fluid from entering the patient’s body and causing irritation and adverse reactions, and is generally often used in patients requiring large amounts of rapid transfusion, infant blood exchange therapy, and in patients with certain condensing hormones present in their bodies. Blood warming can be done in a blood warmer in strict accordance with the instructions, or if there is no blood warmer you can use human body temperature for warming, or put the blood bag that needs to be warmed into 35-38°C warm water, shake it gently, and need to constantly measure the water temperature, and take out the spare for about a quarter of an hour. The warmed blood is usually around 32°C, and care should be taken not to exceed 35°C to avoid destroying blood cells and causing hemolysis. The warmed blood needs to be applied immediately and cannot be put back into the refrigerator.