There are many causes of common bile duct dilatation and different treatment methods, as follows: 1. congenital bile duct dilatation, this belongs to congenital bile duct malformation, a few patients can be operated, most patients have poor surgical results and need symptomatic treatment. 2. stones in the bile duct, due to stones cause obstruction of the bile duct and cause dilatation, in this case the stones can be removed and can be relieved. 3. malignant tumors of the common bile duct In this case, surgical treatment is required. If surgery is not possible, stents can be placed in the bile duct for treatment, but bile duct stents only relieve the symptoms and have no therapeutic effect on the primary disease. In addition, when malignant tumor or occupancy outside the bile duct presses the common bile duct, the dilatation of the common bile duct will also occur, in this case is the treatment of the original disease, the same as the above can also do stent, but only to relieve the symptoms.