The sciatic nerve pain in the left leg is mostly caused by a herniated lumbar disc compressing the nerve, and may also be caused by pear-shaped muscle syndrome. The main reason is that it is related to the strain of prolonged sitting, standing and bending, and there are several ways to deal with it: 1. Rest in bed as much as possible, avoid bending, sitting and standing, and avoid wind and cold. 2. If the pain is severe, intravenous infusion of mannitol can be used to reduce swelling. 4. After the pain is reduced, you can do the swallow fly or the 5-point support method in bed to carry out functional rehabilitation exercises for the lumbar and back muscles, twice a day, about 20 each time.