Bile duct stenosis is often caused by benign and malignant diseases of the bile duct or compression from adjacent organs. Because it is difficult to obtain pathological biopsy samples, clinically diagnosing whether bile duct stenosis is benign or malignant remains challenging. In recent years, with the development and application of medical imaging technologies, techniques such as MRCP, ERCP, and intraductal ultrasonography (IDUS) have gradually been applied in clinical practice, significantly improving the diagnostic level and differentiation between benign and malignant bile duct stenosis. This article summarizes the case data of bile duct stenosis patients who were treated in our center in recent years, analyzing the diagnostic situation of benign and malignant bile duct stenosis using a combination of IDUS, ERCP, and CA19-9.