The biliary system is a monolithic structure that includes the intrahepatic biliary system and the extrahepatic biliary system. The extrahepatic biliary system is primarily a structure consisting of the intrahepatic bile ducts extending out of the liver and converging to form a confluence. The extrahepatic biliary tract anatomy is generally composed of the left and right hepatic ducts converging to form the common hepatic duct, and the common hepatic duct and the cystic duct converging to form the common bile duct. The common bile duct is generally divided into four segments, including the superior duodenal segment, the duodenal segment, the pancreatic segment, and the intra-duodenal wall segment. The lower end of the bile duct and the opening of the pancreatic duct converge to form the sphincter of Oddi, which is equivalent to the valve of the biliary tract. In hepatobiliary surgery, the anatomy of the biliary tract is very important to help identify and prevent biliary tract injuries.