Occupation of the common bile duct indicates that an abnormal obstructive structure is found in the lumen of the normal bile duct during an imaging examination, which may be due to a tumor. The common bile duct is a hollow internal duct that is surrounded by pancreas, liver and other tissues and organs. If abnormal structures are found in the hollow part of the common bile duct that makes the duct narrow or not smooth during the examination of the common bile duct by CT or ultrasound, it is called an occupancy, and the cause of the occupancy may include tumors and other reasons. Occupation of the common bile duct can easily lead to obstruction of the common bile duct, resulting in poor bile drainage, which in turn can lead to liver function damage and jaundice. It is recommended to further undergo enhanced CT, magnetic resonance, puncture biopsy and other examinations to clarify the cause of the disease and standardize and systematic treatment.