Sudden left waist pain at night can be caused by the following reasons: first, kidney stones, when the kidney stone is large, walking down, through the ureter, stuck in the ureteral stenosis, there can be symptoms of back pain, which is often colicky, can be aggravated by paroxysms, and can be accompanied by hematuria, which should be early examination of the kidneys of the color ultrasound or CT as well as the urine test, to early diagnosis and early treatment. Secondly, renal vascular disease, when the arteries of the kidneys are blocked, for example, due to thrombosis or embolism, sudden back pain, often tear-like pain, then we should check the renal imaging for early diagnosis and treatment. Thirdly, tumor rupture, if there is tumor in kidney, when rupture occurs, back pain can occur, often with tear-like or cut-like pain, at this time, CT, ultrasound and MRI of kidney should be taken for early diagnosis and treatment.