Numbness of legs in the elderly is mainly caused by physiological factors, lumbar spine lesions, peripheral neuropathy, spinal cord cervical spondylosis and other factors. 1. Physiological factors: the elderly keep a position for a long time, the blood flow of the legs is blocked, there will be physiological numbness of the legs, reasonable activities can be improved on their own. 2. Lumbar spine lesions: for example, lumbar disc herniation or lumbar spinal stenosis may cause serious compression of the nerves that innervate the lower limbs, which may easily cause numbness in the legs, accompanied by radiating pain in the lower limbs, lumbar pain and other symptoms. 3. Peripheral neuropathy: For example, diabetes-induced peripheral neuropathy or alcoholism-induced peripheral neuropathy can cause numbness in the legs, which may be accompanied by tingling and other symptoms. 4. Spinal cord cervical spondylosis: it may be related to long-time work, when the spinal cord is compressed, it is easy to cause numbness in the lower limbs, which may be accompanied by numbness in the upper limbs, unsteady gait, difficulty in walking and other symptoms. If the numbness in the legs lasts for a long time and there are other abnormal manifestations, it is recommended to consult a doctor for examination and treatment.