The injection site and method of BCG is intradermal injection in the deltoid muscle of the upper arm. BCG is a vaccine used for the prevention of tuberculosis, the injection site is the upper arm deltoid muscle, the injection method is to use 75% alcohol to thoroughly disinfect the skin of the upper arm deltoid muscle area, and after the alcohol dries, the vaccine is injected into the upper arm deltoid muscle subcutaneously by hypodermic injection. After BCG vaccination, the patient should stay at the vaccination site for at least 30 minutes. After returning home, the patient should pay attention to nursing care and self-monitoring, and go to the hospital immediately for treatment if he/she feels unwell. After BCG vaccination, the injection site usually breaks down, scabs, peels off, and eventually leaves a BCG scar, which is a normal reaction after vaccination. If BCG vaccination is overdosed, it may lead to a larger area of ulceration, so be careful not to overdose, and pay attention to the accurate dose, shake the vaccine well, and pierce the skin superficially.