The most common causes of pain behind the left lower back in female patients are the following: 1. Left-sided adnexitis, after the occurrence of left-sided adnexal inflammation, it will involve the left lower back, thus leading to pain behind the left lower back. 2. urinary stones, manifested as pain behind the left lower back, often accompanied by abdominal pain, abdominal pain to the perineum, suggesting that patients improve urinary routine examination, urinary ultrasound or CT examination. 3, 3, lumbar muscle strain, the patient appears the left lumbar back pain, after activity aggravated, after rest relief, can be treated with topical ointment. 4, lumbar disc herniation or lumbar spinal stenosis, manifested as the left lumbar back pain, often accompanied by the left lower limb pain and numbness, the patient is recommended to improve the intervertebral disc CT examination. So there are many diseases that cause pain in the back of the left back, it is recommended that patients must go to the hospital for a systematic examination to clarify what the cause is and to treat accordingly.