Numbness of legs after standing for a long time may be caused by physiological reasons, or pathological reasons such as lumbar spine disease and lower limb vascular disease. 1. Physiological changes: due to prolonged standing, poor blood circulation in the lower limbs, some people may experience numbness in the legs, most of which can be relieved after activities. 2. Lumbar spine disease: commonly seen in lumbar disc herniation, spinal stenosis, lumbar spine slippage and other lumbar spine degenerative diseases, prolonged standing will cause localized nerve root compression aggravation, may appear leg numbness and other symptoms. 3. Lower extremity vascular disease: common in the lower extremity arterial embolism, varicose veins of the lower extremity, standing for a long time will make the lower extremity ischemia or venous reflux is impeded, caused by the nerve ischemia, hypoxia, edema and other changes, may appear leg numbness symptoms. Standing for a long time leg numbness may also have other reasons, it is recommended to go to the hospital in a timely manner, further examination to clarify the specific causes of the disease to give targeted treatment.