Persistent pain in the left side of the waist may have the following causes: First, kidney disease, when there are tumors or stones in the kidneys, there can be persistent pain in the kidneys, often soreness or colic, which can have paroxysmal intensification, then we should take early ultrasound, CT and urine tests of the kidneys for early diagnosis and early treatment. Second, kidney vascular disease, when the kidney artery blockage, such as infarction or embolism, there can be persistent pain in the back, then early kidney angiography should be performed for early diagnosis and early treatment. Third, acute sprain of the lumbar region, acute sprain of the lumbar region can appear continuous pain in the lumbar muscles, which is often sore and can be accompanied by limited lumbar activities, which should be investigated and examined early to exclude other diseases for early diagnosis.