There are several possible causes of pain on the back side of the waist: first, lumbar dorsal fasciitis, lumbar dorsal fasciitis is often caused by strain and cold, which can lead to pain on the back side of the waist; second, lumbar muscle strain, lumbar muscle strain is due to chronic muscle damage and pain on the back side of the waist, which should be diagnosed by relevant investigations and examinations to exclude other diseases; third, kidney diseases, when the kidneys have tumors, inflammation When the kidneys have tumors, inflammation or stones, pain on the posterior side of the waist can also occur, then the kidneys should be diagnosed by ultrasound, CT, imaging, and if necessary, urine tests; fourth, lumbar spine diseases, when the lumbar spine has lumbar disc herniation or lumbar spinal stenosis, slippage, pain on the posterior side of the waist can also occur, then the lumbar spine should be diagnosed by CT, nuclear magnetic examination; fifth, rheumatoid or ankylosing spondylitis Fifth, rheumatoid or ankylosing spondylitis can also cause pain on the posterior side of the back.