The blood of human body is 7%-8% of body weight under normal condition, and the blood volume is about 4200ml-4800ml according to the weight of adult 60kg. when the human body suffers blood loss up to 10% or so, the body will keep the blood volume balanced with its own inter-tissue fluids provided by the blood circulation to maintain the normal functioning of the body without any abnormality. When the blood loss of the organism reaches 10%-20%, the human body will experience accelerated heart rate, postural hypotension, etc., and need to replenish fluids to maintain blood circulation. When the blood loss of the organism reaches 20%-30%, supplementation of body fluids should be carried out together with appropriate supplementation of red blood cells in order to improve the oxygen-carrying capacity of the blood. When the body is deprived of more than 30% of blood, whole blood and fluids should be supplemented to maintain the body’s blood volume. The body’s blood must be maintained in sufficient quantity, not lacking in useful components, and must not be affected by anemia, hypoproteinemia, severe infections, coagulation abnormalities, and other conditions that affect health.