There are several possible causes of left posterior lumbar pain in men: First, lumbar muscle strain, long-term work or labor with the left side of the waist can occur chronic injury to the left side of the lumbar muscles, and thus lumbar muscle strain can occur the symptoms of lumbar pain. At this time, it is necessary to carry out lumbar-related examinations to exclude other diseases for diagnosis. Second, kidney disease, kidney nephritis, kidney tumors or kidney cysts, can appear the symptoms of left-sided lumbar pain, can also be accompanied by urinary symptoms such as hematuria, proteinuria, urine tests and kidney ultrasound, CT, urography, etc. for diagnosis and treatment.