The injection location of low molecular heparin sodium is usually chosen for subcutaneous injection or intravenous administration. In the choice of subcutaneous injection, the abdomen is the best injection location, because the abdomen has a large injection area, more subcutaneous fat, relatively few capillaries, constant subcutaneous temperature, fast drug absorption, and is not affected by movement. In the injection, choose the abdomen 5cm above the umbilicus or 5cm below the umbilicus as the upper and lower boundaries, left and right 5cm inside and outside the midclavicular line, avoid the umbilicus, alternate left and right injections twice, the injection point spacing 2cm. massage the local skin for 2min before injection until the skin is red, lie flat and sit on your knees, disinfect the local skin, ask the patient to lift the skin of the abdominal wall, form a fold, vertical angle, pull out the needle cap for injection.