Sudden pain in the waist may have the following causes: first, acute sprain of the lumbar muscles, there is often a clear history of lumbar sprain, then there will be acute muscle damage and lead to sudden pain; second, small joint disorders, common in the elderly, due to degeneration of the lumbar spine and lead to small joint disorders, or young people due to acute lumbar sprain and lead to small joint disorders, then there can be sudden pain in the waist; third, urinary stones, when the kidney stones downward travel stuck in the ureteral stenosis, there can be sudden pain in the waist; Thirdly, urinary stones, when kidney stones travel downward and get stuck in the ureteral stenosis, there can be sudden pain in the waist, often colic, which can be intensified paroxysmally and can be reflected to abdominal pain, then the relevant urological imaging and ultrasound examination should be performed for diagnosis; fourthly, renal vascular diseases, when the arteries of the kidney are blocked, such as thrombosis or embolism, sudden pain in the waist can occur. When the artery of kidney is blocked, such as thrombosis or embolism, sudden pain in the back, often tearing pain, can be accompanied by pain in the abdomen, then the relevant angiography and CT, MRI should be performed for diagnosis.