The left side of a woman’s back pain can be caused by the following causes: first, strain on the left side of the lumbar muscles, when long-term work with one side of the waist, can lead to chronic injury to the muscles of one side of the waist, and lead to pain in the lumbar muscles, then to check and examination, to exclude other diseases to diagnose. Second, lumbar dorsal myofasciitis, one side of the lumbar dorsal myofasciitis patients can also have the symptoms of one side of the lumbar pain, then to early physical examination, early diagnosis after physical therapy and oral medication treatment. Third, kidney disease, when the kidney has nephritis or kidney tumor, in the early stage can also have one side of the waist kidney area pain, then we should check the kidney ultrasound, CT and urine tests, if necessary, to do urography to early diagnosis and early treatment.