Standing for a long time leg swelling may be due to soft tissue fatigue, cold environment stimulation and other physiological reasons, may also be due to heart disease, lower limb vascular disease and kidney disease and other pathological factors. 1. Physiological reasons: the lower limbs themselves are centrifugally distant, blood circulation is relatively poor compared to the upper limbs and other parts of the body, standing for too long may lead to fatigue of the soft tissues of the lower limbs, resulting in the accumulation of metabolic products, slowing down of blood flow, affecting the blood circulation in the lower limbs and the symptom of swollen legs. In addition, blood flow will be slowed down in cold environment, which may also lead to the above symptoms. 2. Pathologic factors (1) Heart disease: patients with heart disease may suffer from blood stasis in the circulation due to systolic and diastolic dysfunction of the heart, which may also lead to the symptoms of leg swelling after standing for a long time, and common diseases such as right heart failure or total heart failure. (2) Lower extremity vascular disease: Lower extremity vascular disease can cause venous return obstruction, resulting in blood stagnation and leg swelling, such as lower extremity deep vein thrombosis, varicose veins of the lower extremity, and so on. (3) Kidney diseases: Kidney diseases cause generalized edema due to sodium and water retention in the body, and also cause leg swelling due to standing for a long time. Such as glomerulonephritis and renal failure and other diseases. Standing for a long time by the symptoms of leg swelling sometimes can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results in order to make an accurate judgment, it is recommended that the cause of the disease under the guidance of a doctor.