Swelling of the legs and feet when sitting is usually seen in patients with venous insufficiency of the lower extremities, because the muscle pump of the lower leg does not function in a sitting position, and the lower leg cannot promote venous reflux through muscle contraction, and because of problems with the valve, there is gradual swelling of the legs or feet. Once this condition occurs, patients should consult the vascular surgery department as soon as possible and have ultrasound examination of the deep and superficial veins of the lower limbs to clarify the length and scope of the disease. After the diagnosis is clear, the condition can be relieved by using elastic medical stockings and taking oral medication such as Avalanche or Mizarin to avoid the gradual aggravation of edema and the gradual hardening of the skin with elephant leg-like changes.