There are several possible reasons for the pain in the left side of the back of the male: first, kidney disease, when the kidney has a tumor, inflammation or cysts, stones, there can be a pain in the back of the side of the back, to early ultrasound, CT examination of the kidney, as well as urine laboratory tests, to carry out early diagnosis and early treatment. Second, lumbar muscle strain or lumbar muscle tumor, when the lumbar muscle strain, can appear one side of the lumbar muscle pain, if the muscle tumor, can also appear in the lumbar muscle pain, to carry out the relevant ultrasound, CT, nuclear magnetic examination, to carry out early diagnosis and early treatment.