China’s blood donation law stipulates that the amount of blood donated by healthy citizens without compensation is generally between 200-400ml, and generally not less than 200ml, and generally not more than 400ml, because between 200-400ml, there is no obvious impact on human health, and at the same time, it can meet the clinical application, because a person’s blood volume is proportional to his or her own weight, and generally, the weight of his or her own blood It accounts for 7%-8% of one’s own body weight. The heavier one’s weight is, the more blood will be in one’s body, and the lighter one’s weight is, the less blood will be in one’s body. The decision to donate blood should be made in relation to one’s own weight. If a person is too light, for example, an adult male, weighing around 50kg, donates 400ml of blood, often the amount of blood donated will be more than 1/10 of his own blood volume, and he will be prone to pallor, dizziness, weakness and other uncomfortable symptoms after donating blood. Therefore, a lighter person can donate around 200ml of blood and a heavier person can donate 400ml.