Dilatation of the common bile duct over 2cm is considered serious and needs to be treated promptly according to the cause of the dilatation of the common bile duct. 1. Choledochal stone: For choledochal dilatation caused by choledochal stone, surgery can be chosen, and the choledochal dilatation will be restored after the stone is removed. 2. Congenital choledochal dilatation: For patients with congenital choledochal dilatation, surgery can be chosen to remove the dilated choledochal duct, and active symptomatic treatment. If not treated timely, it may lead to cholangiocarcinoma. 3. Tumor: for cholangiocarcinoma, pancreatic head cancer and other tumors leading to choledochal dilatation, this is the most serious case, which needs radical surgical treatment for the tumor, and the choledochal dilatation will be relieved after relieving the tumor’s pressure on the choledochal duct. Patients with dilated common bile duct are recommended to seek medical treatment in time and undergo detailed examination in order to clarify the cause of dilated common bile duct and then adopt appropriate treatment plan.