Proper blood donation is not seriously harmful to the body and can help others. Before donating blood donors can drink a small amount of light salt water to help expand the donor’s blood volume and avoid symptoms such as panic, dizziness, nausea and vomiting when the donor gives a large amount of blood. Although the blood donor drinks in light salt water has a certain dilution effect on the blood, it does not affect the normal use of the transfused blood. Blood donors must maintain adequate energy intake before donating blood. They should not donate blood in an empty stomach, and if necessary, they can eat a moderate amount of cookies in small quantities before donating blood, but do not eat too greasy food. Proper energy supplementation can effectively prevent the donor from experiencing hypoglycemia after blood donation. Patients should take sufficient rest after blood donation to avoid overexertion and staying up late, which may cause physical damage.