The pain on the left side of the waist in men is first considered to be a strain disease. Because men bend over for a long time to work with heavy loads or get cold and other factors, the left side of the waist muscle is chronically injured. It produces aseptic inflammation, stimulates peripheral nerves, and causes pain and discomfort. Secondly, it can be seen in degenerative diseases, such as lumbar hyperosteogeny, osteoporosis and lumbar disc herniation, which may stimulate and compress the nerves and cause left side low back pain. In addition, left side low back pain may also be a disease of abdominal organs, such as diseases of the urinary system, renal colic, kidney stones, etc., which can cause left side low back pain. Therefore, it is recommended that men should go to the hospital in time for examination and treatment for left side low back pain.