Leg weakness should be analyzed in the context of whether the patient has unilateral leg or bilateral leg weakness, as well as the form and duration of the patient’s leg weakness, and previous underlying diseases, which should be considered from three aspects: First, caused by cerebrovascular disease. Second, caused by lumbar intervertebral disc and lumbar spinal stenosis problems. Third, to consider whether the lower extremity blood vessels have occlusion, venous thrombosis caused by leg sensory weakness. If the patient has hypertension, diabetes, cerebral arteriosclerosis and other diseases of the elderly, when there is weakness in the right leg or weakness in the left leg, it must be considered that the cerebrovascular disease may be caused by cerebral infarction or transient cerebral ischemic attack, and it is necessary to visit the hospital for physical examination and to do magnetic resonance brain function imaging of the head to make a clear diagnosis before giving treatment. And if the patient has a history of lumbar disc herniation or lumbar spinal stenosis, the symptoms of feeling weakness in both legs may appear, and the patient may have lumbar pain at the same time. Patients with lower extremity atherosclerosis and occlusion may feel weakness in both legs, especially after walking, which is usually accompanied by intermittent claudication.