The left posterior lumbar pain in female patients is clinically common due to the following three major diseases: 1. lumbar muscle strain or lumbar disc herniation caused by long-term bending activities, which usually requires further lumbar spine CT examination, and treatment mainly involves rest and lying down. 2. The urinary tract ultrasound or routine urine examination and, if necessary, urine culture. In the case of urinary tract infections, a sensitive antibiotic is usually required. If it is a urinary tract stone, usually medication is used to remove the stone, larger stones need to be lithotripsy, and if necessary, surgery to remove the stone. 3. mainly female pelvic inflammatory disease, secondary to the left lumbar pain and discomfort, usually need further pelvic ultrasound examination to clarify the diagnosis. Treatment is mainly conservative, such as anti-inflammatory treatment, and even surgery is needed if necessary.