There are many reasons for pain in the back of the waist, such as lumbar spine disease, lumbar dorsal musculoskeletal fasciitis, renal disease, and systemic factors. 1. Lumbar spine diseases: Suffering from lumbar disc herniation, lumbar spinal stenosis, lumbar spine tuberculosis, lumbar spine infections and other diseases can cause pain in the back of the lumbar spine, which will be accompanied by obvious limitation of lumbar activities. 2. Lumbar dorsal myofasciitis: Lumbar dorsal myofasciitis is mainly caused by long-term weight bearing, cold stimulation and overstrain of the lumbar back, which will cause pain behind the waist. 3. Kidney diseases: suffering from pyelonephritis, kidney stones, kidney tumors and other diseases can also cause pain in the back of the waist, which needs to be clearly diagnosed by CT and ultrasound of the kidney. 4. Systemic factors: Suffering from systemic lupus erythematosus, ankylosing spondylitis, rheumatoid arthritis and other diseases can also cause pain behind the waist due to inflammation attacking the waist. The causes of pain behind the waist are very many, after the emergence of uncomfortable symptoms, it is recommended that patients can go to the hospital to take a systematic examination, a clear diagnosis, and after diagnosis to take standardized treatment, do not ignore the symptoms.