Common causes of double lower extremity atherosclerotic occlusion include smoking, diabetes, dyslipidemia, obesity, hypertension and homocysteinemia. 1. Smoking: Smoking increases the morbidity rate by 2 to 5 times. Tobacco contains thousands of different chemicals, among which rutin is a kind of pro-coagulant, which can activate Factor X, which plays a key role in the coagulation process, and make the blood in a high coagulation state. Patients who smoke are not only at a higher risk of amputation, but also have a reduced effect of endovascular or surgical bypass procedures. 2. Diabetes mellitus: Diabetes mellitus increases the incidence of atherosclerotic occlusive disease (AOS) by two to four times, and AOS is a common complication of diabetes mellitus. 3. Dyslipidemia: Dyslipidemia includes elevation of serum total cholesterol and triglyceride and reduction of HDL, which will cause accelerated progression of atherosclerosis. 4. Obesity: Obese people generally have metabolic abnormalities, which often lead to the progression of atherosclerosis. 5. Hypertension: Hypertensive patients are more likely to suffer from atherosclerosis than normal people due to factors such as platelet activation level, endothelin, angiotensin and insulin resistance. 6. Hyperhomocysteinemia: homocysteinemia is an independent risk factor for atherosclerosis, and about 30% of patients with atherosclerotic occlusive disease have hyperhomocysteinemia. If atherosclerotic occlusive disease of both lower limbs is diagnosed, early standardized treatment is recommended to reduce the adverse effects of the disease.