Bile duct stones are divided into primary and secondary types. Primary bile duct stones refer to stones that originate in the bile duct system (including the intrahepatic bile duct). The nature of the stones is mostly pigmented mixed stones containing a large amount of bilirubin calcium. There must be stones in the gallbladder. In my country, most bile duct stones belong to this category. Secondary bile duct stones refer to stones formed when stones in the gallbladder enter the common bile duct through the enlarged cystic duct. The shape and nature of the stones are mostly the same as those in the gallbladder. Most of them are multifaceted cholesterol mixed stones. Due to secondary bile duct infection, the outer layer of the stones has bilirubin calcium deposits.