The blood donation law in China provides for the promotion of blood donation by healthy citizens without compensation, because in general, blood donation by healthy citizens without compensation has no obvious effect on human health, does not affect human health, and can alleviate the tight blood supply situation in our country. At the same time, blood donation is a sign of responsibility and compassion. During the process of blood donation, some people have certain accidents due to the process of blood donation. One of the most common accidents is the occurrence of syncope, for example, some people suddenly become pale, unconscious and faint during the process of blood donation, which is usually related to nervousness and other reasons. Most people can recover after being in bed with oxygen. When donating blood for free, some women may experience anemia afterwards because women are prone to anemia and when donating blood for free, it may easily trigger or aggravate the symptoms of anemia. Also, some people may experience a short period of decreased immunity. These are the common adverse effects of blood donation.