CT can detect bile duct stones and also clarify the degree of dilatation of the bile ducts, as well as detecting stones that cannot be detected by X-ray and ultrasound. CT is able to show images of different levels of the biliary system and determine the cause and location of biliary obstruction, it is a more sensitive means of examination, and is better than ultrasound for the diagnosis of intra- and extra-hepatic bile duct stones. CT can clearly show the degree of dilatation of the bile ducts while displaying the stones. However, CT is not a commonly used test for choledocholithiasis, and is often used when ultrasound is not clear. Currently, ultrasound is the preferred test for cholelithiasis, which can detect more than 90% of the stones, and can also find out the degree of dilatation of the bile ducts and the site of obstruction, the diagnostic effect is slightly worse than CT, but the examination is convenient.