Left leg pain while the right leg is fine is mainly considered to be caused by poor posture of sitting or standing for a long time, which leads to pressure or long-term tightness of the left leg muscles and poor local blood circulation, resulting in the performance of left leg pain. Usually after rest will gradually relieve, if persistently not relieved, need to be alert to disease factors caused by left leg pain. Common diseases mainly include lumbar spine diseases, left leg lesions, etc.: I. Lumbar spine diseases: common in lumbar disc herniation, if the herniated disc nucleus pulposus is biased to the left side, compressing the left spinal nerve root and dural sac, there will be soreness, numbness and weakness of the left leg. Second, left leg lesions: 1, left knee osteoarthritis: due to the stimulation of inflammation will appear swelling and pain of the left knee, the left leg may be involved in the situation of soreness; 2, left hip joint diseases: such as osteoarthritis of the hip joint, left hip joint tear, and even left hip ischemic necrosis of the femoral head and other diseases may appear left leg soreness; 3, left lower limb vascular diseases: common lower limb venous thrombosis The diseases such as lower extremity vein thrombosis, lower extremity varicose vein and so on, appear the situation of poor local blood circulation, thus appear the situation of left leg pain. In general, if the degree of left leg pain is relatively light, you can pay attention to rest and observe the improvement of symptoms. If it does not improve, it is recommended to go to the hospital in time to clarify the cause of the disease, and then targeted treatment.