Intramuscular injection is currently a very common method of drug injection, the liquid of the drug through the syringe into the human body, so as to achieve the effect of the treatment of disease, to the hospital for injection and infusion, will encounter intramuscular injection. The angle of intramuscular injection needs to be determined according to the muscle group selected and the different types of liquid input. The most commonly used method is intramuscular injection of the gluteus maximus muscle, which is more developed, and the needle tip is at an angle of 90 degrees to the skin when intramuscular injection is performed, that is, vertically. However, if intramuscular injection is performed in the biceps muscle, it is recommended that the needle tip and the skin be at an angle of 30-45 degrees for intramuscular injection. In addition, for subcutaneous injections, such as in the abdominal muscles or in the biceps femoris or triceps femoris, it is recommended that the skin and the vertical distance be at an angle of 30-45 degrees.