There are many causes of lower extremity edema, which can be divided into systemic edema and localized edema factors. Systemic edema factors are mainly seen in heart failure, renal disease, liver cirrhosis, and endocrine. Local edema factors are mainly vascular and lymphatic circulation disorders and inflammatory factors in the local limbs. Systemic edema factors include: 1. heart failure: stasis of the body circulation occurs in right heart failure, and edema is mainly in the lower limbs. 2, nephritis and nephropathy, etc.: initial eyelid and facial edema, and as the disease progresses edema may appear in both lower extremities. 3. Cirrhosis decompensation stage: patients with liver function decompensation, hypoproteinemia and ascites are obvious, and edema of both lower extremities may appear. 4, endocrine factors: such as hypothyroidism, the edema is non-depressed, mainly in the face and upper limbs, and in severe cases, the edema of both lower limbs may appear. Local factors are mainly seen in obstruction of vascular and lymphatic circulation. Lymphatic reflux obstructive edema includes filariasis and lymphangitis; venous reflux obstructive edema includes venous thrombosis and varicose veins; inflammatory edema includes cellulitis, dermatitis, boils, carbuncles, high temperature and chemical burns. There are also physiological edema factors, such as high temperature, pregnancy-induced edema, premenstrual tension syndrome, and sedentary, which can cause lower extremity edema. There are many causes of lower extremity edema, and the cause should be further defined so that the cause can be treated.