Intramuscular injection is a common clinical route of drug delivery, and is a treatment method of injecting drug solution into muscle tissue through a syringe. Intramuscular injections should be performed in areas where muscle fibers are thick and far from large blood vessels and nerves. Suitable sites for intramuscular injection are gluteus maximus, upper arm deltoid, gluteus medius, gluteus minimus and lateral femoral muscle, etc. 1. gluteus maximus: the horizontal line extending from the apex of the gluteal cleft to both sides and the vertical line passing through the highest point of the iliac crest intersect to form four quadrants, the outer upper quadrant avoiding the inner corner is the injection area, suitable for adults, not for infants and children; 2. upper arm deltoid: the injection area is 2-3 horizontal fingers below the peak of the shoulder on the outer side of the upper arm, the upper arm The upper arm deltoid muscle is weak, suitable for small doses of injection, and often used for vaccination; 3. gluteus medius and gluteus minimus: the tips of the index and middle fingers are placed at the anterior superior iliac spine and the lower edge of the iliac crest, and the injection area is the inner corner between the index and middle fingers. The fatty tissue of the gluteus medius and gluteus minimus is weak, and the distribution of blood vessels and nerves is also small, so it is suitable for infants and young children for intramuscular injection treatment; 4. lateral femoral muscle: the injection area is the lateral part of the mid-thigh, generally 10 cm below the hip joint to 10 cm above the knee joint in adults, with a range of about 7.5 cm in width. The lateral femoral muscle has fewer large blood vessels and nerve trunk distribution, and the area suitable for injection is larger, which can be used for multiple injections. In addition, intramuscular injection is not recommended when the skin at the injection site is infected, hard knotted, wounded, ulcerated, etc., and when injecting a strong stimulating drug or using a large amount of drug. Injections should be performed under aseptic operation, and patients should avoid excessive tension when injecting to avoid causing muscle contraction to affect the injection. Long-term intramuscular injections should be properly replaced at the injection site to avoid local hard nodules.