The old numbness of legs may be caused by physiological factors, lumbar spondylosis, cervical spondylosis, diabetic peripheral neuropathy, cerebrovascular lesions and other factors. 1. Physiological factors: in the work and life, keep a position too long, resulting in leg pressure, will make the legs old numbness, should improve the bad posture, reasonable activities. 2. Lumbar spine lesions: such as lumbar spinal stenosis, lumbar disc herniation, etc., can cause compression of the nerves that innervate the lower limbs, which often cause numbness of the legs, and may be accompanied by lumbar pain and radiating pain in the lower limbs and other symptoms. 3. Cervical spondylosis: for example, spinal cervical spondylosis, which may be related to neck trauma, prolonged bowing of the head and other factors, when the spinal cord is obviously compressed, there will be numbness of the legs, which may be accompanied by numbness of the upper limbs, and in severe cases, it may lead to paralysis of both lower limbs. 4. Diabetic peripheral neuropathy: diabetes mellitus for a long time, poor control of blood sugar, can cause peripheral neuropathy, will often appear leg numbness, foot numbness, hand numbness and other symptoms, accompanied by drinking, eating, fatigue and other symptoms. 5. Cerebrovascular lesions: the existence of hypertension, high blood pressure, high blood fat, diabetes and other pathologies, may induce cerebral infarction, will often appear leg numbness, may also be accompanied by numbness of the upper limbs, dizziness and other symptoms. Legs old numbness, and the existence of other abnormal performance, exclude the physiological factors, it is recommended to seek medical examination and treatment as soon as possible, to avoid causing other complications.