Leg pain is often seen in trauma, lumbar intervertebral disc herniation, lower extremity arterial occlusive disease and other diseases. 1. Trauma: If you suffer from trauma, impact and other factors, can cause serious damage to the soft tissues of the lower limbs, or even fracture, there will be intolerable leg pain can not walk, accompanied by local skin bruising and muscle swelling. 2. Lumbar disc herniation: if the leg pain suddenly attacks when walking, accompanied by lumbar pain, radiating to the lower limbs, consider the possibility of lumbar disc herniation, mainly due to the protruding disc compression of the nerves. 3. Lower extremity arterial occlusion: long-term history of heavy smoking, lower extremity vascular thrombosis, diabetic vasculopathy and other conditions can easily lead to lower extremity arterial occlusive disease, there will be severe pain in the legs, unable to walk phenomenon. There are many other factors that lead to unbearable leg pain and inability to walk, it is recommended to seek medical examination in time to clarify the cause of the disease and give appropriate treatment or therapy.