The main causes of weakness in both legs are as follows: 1. coronary heart disease, heart failure, due to insufficient blood supply to the myocardium, the heart function is affected, the ejection efficiency decreases, the peripheral tissues will face insufficient blood supply, lack of oxygen, thus manifesting as weakness, weakness in both legs. 2. severe atherosclerosis in both lower limbs, in this case, the lower limbs also have insufficient blood supply and weakness in both legs, doing ultrasound of arteries in both lower limbs can help to make a clear diagnosis, and if necessary, medication or intervention can be used. 3. If necessary, medication or interventional therapy can be used. 3. Severe anemia, due to the decrease in hemoglobin, the body’s ability to deliver oxygen to the tissues decreases, thus showing weakness in the legs. 4. Patients with hypokalemia, because the blood potassium is below normal levels, the patient can show abdominal distension, weakness, weakness in the legs and other non-specific manifestations. Early potassium supplementation to correct electrolyte disorders can help change this phenomenon. 5, cervical spondylosis, when the cervical spine appears to compress the nerve, some patients will appear two legs sinking, walking weakness.