The main measures to prevent infection when injecting are aseptic operation, strict sterilization, do not enter the needle in the inflamed area, etc. 1. Aseptic operation: wash hands before injection, wear a mask, neatly dressed and so on. The needle used in sterile syringe must be taken by sterile forceps, and the piston, inner surface of syringe, nipple and needle tip and stem should be kept sterile. 2. Strict disinfection: use two percent tincture of iodine and seventy percent deiodination of ethanol for routine disinfection of the injection site, and disinfect the skin of the injection site with a diameter of more than 5 cm to avoid bacteria entering the body with the needle and causing infection. 3. Do not enter the needle in the inflammation site: patients who need long-term injections, the injection site should be used alternately, not in the pus infection, hard knots, inflammation or skin disease site into the needle. After injection, the skin should be kept dry, and the injection site should not be exposed to water for 24 hours, and timely observation should be made to prevent infection.