Leg numbness may be lumbar disc herniation, pyriformis syndrome, common peroneal nerve injury or cerebrovascular disease, etc. It may also be physiological factors. 1. Lumbar disc herniation: it is because the herniated nucleus pulposus compresses the nerve and causes edema of the nerve root, so the symptoms of numbness of the legs will appear, and some of them will be accompanied by pain and weakness of the lower limbs, which can be clearly diagnosed through lumbar MRI films. 2. Piriformis syndrome: it is because the adhesion or swelling of the piriformis muscle compresses the sciatic nerve which passes through the piriformis muscle, causing the numbness of the sciatic nerve innervation area, and the clinical symptom of numbness of the leg appears. 3. Common peroneal nerve injury: usually caused by trauma or peroneal nerve compression, mainly manifested as numbness and weakness of the calf, and severe patients can have foot drop, which can be clearly diagnosed by electromyography. 4. Cerebrovascular disease: for example, cerebral infarction or cerebral hemorrhage, hemiplegia, one side of the limb movement is unfavorable, numbness. The diagnosis can be clarified by cranial CT. 5. Physiological factors: Numbness of the legs may be caused by long time immobilization or pressure on the same part of the legs, which can be relieved by rest and massage. In addition, cervical spondylosis or thoracic spinal stenosis may also be involved, which can be initially diagnosed through nuclear magnetic resonance imaging (NMRI) and electromyography (EMG). If there is prolonged numbness of the legs, or the numbness persists without relief, you need to go to the hospital for examination.