Leg swelling in the elderly may be caused by long-term sedentary, malnutrition, nephritis and other reasons. 1. Prolonged sedentary: prolonged sedentary can cause obstruction of blood and lymphatic reflux in the lower limbs and stagnation in the lower limbs, resulting in edema. 2. Malnutrition: it is mainly caused by the lack of food due to various factors. As the patient’s body can have protein deficiency, thus causing hypoproteinemia and malnutrition edema. 3. Nephritis: it is a group of renal diseases caused by a variety of reasons that lead to inflammatory lesions in renal tubules and surrounding tissues, thus leading to kidney injury. Patients with large amounts of proteinuria, resulting in a decrease in plasma albumin, will appear lower extremity edema. When patients with nephritis consume more salt and water, or when they are combined with hypertension, sodium retention will occur, which can also lead to edema in the lower limbs. In addition, it is recommended that elderly people with leg swelling go to the hospital in time to do relevant examinations and follow the doctor’s instructions for treatment to avoid delaying their condition.