Bile duct cancer can be cured by surgery in only a few patients, and the incidence of bile duct cancer in China has increased significantly in recent years. The main clinical manifestation of cholangiocarcinoma is obstructive jaundice, and the average survival time of untreated cholangiocarcinoma is about 6 months from the appearance of clinical symptoms, and Klatskin [1] has long pointed out that most patients with cholangiocarcinoma do not die from extensive metastasis, but mainly from complications such as progressive impairment of liver and kidney function or biliary tract infection or liver abscess due to long-term biliary obstruction. Therefore, controlling tumor growth and maintaining bile duct patency become the key of palliative treatment for bile duct cancer. Biliary interventions aiming at maintaining the physical patency of bile ducts play an important role in the treatment of bile duct cancer. Many patients with bile duct cancer have obvious jaundice at the time of consultation, and some of them have difficulty in tolerating surgical treatment such as radical resection because of long bile duct obstruction and poor general condition. Therefore, it is recommended to drain the bile duct first to reduce the damage of jaundice on liver and kidney function, improve the general condition, and prevent acute liver and kidney failure after radical resection. Preoperative biliary interventions mainly include transendoscopic bile duct drainage and PTCD, which, in addition to therapeutic effects, can further clarify the site and scope of biliary tumors and provide a basis for determining the appropriate surgical plan. Endoscopic bile duct placement mainly includes nasobiliary duct drainage (ENBD) and bile duct placement with plastic stent or metal stent (ERBD or EMBD), which has the following advantages: (1) it is easy to observe bile drainage and cholangiography, (2) it can be flushed in time if there is obstruction, and bile culture can be performed in case of bile duct infection, and anti-infective drugs can be injected through this catheter, and (3) it is not necessary to perform endoscopy again if the nasobiliary duct is removed. Endoscopy is not necessary if the nasobiliary duct is removed. ERBD can maintain the physiological condition of bile drainage without the disadvantage of bile loss, which is conducive to the rapid recovery of patients without throat discomfort and activity restriction. In addition, if the patient is found to be unfit for surgery during the preoperative preparation, there is no need to perform biliary drainage again, thus reducing the patient’s pain and financial burden, however, ERBD cannot directly observe the bile drainage and is prone to obstruction and need to change the tube again. If the lesion is extensive, multiple stent drains need to be placed, which is difficult, and EMBD is mostly used for palliative drainage for inoperable patients, which is difficult and expensive to remove after placement. Endoscopic biliary drainage can be performed with a balloon or probe to dilate the stenosis. The bile duct dilating balloon is shorter and suitable for patients with short stenoses, while the probe dilator is suitable for proximal stenoses and more severe stenoses. Papillary sphincterotomy (EST) can often be performed at the same time to enhance the regression effect and reduce complications such as pancreatitis after endoscopy. Although preoperative endoscopic biliary drainage is safe and effective, it can cause varying degrees of inflammation and edema in and around the bile duct, thus making the procedure more difficult. For patients who cannot successfully perform endoscopic bile duct placement, PTCD can be performed, and some units are currently performing 3D PTCD under MR or CT guidance, and the author advocates performing PTCD under the guidance of a general ultrasound probe, which has a success rate of more than 95% for bile ducts over 3 mm. For patients who can pass the guidewire through the stenotic segment, a PTCD tube can also be placed into the duodenum along the guidewire. If a single PTCD tube can only drain bile from the local liver, multiple PTCD tubes can also be performed to drain the bile. However, PTCD should be performed with caution in patients with high ascites or poor coagulation, and for patients who cannot distinguish between benign and malignant strictures, percutaneous hepatic cholangioscopy (PTCS) can be performed for biopsy [2]. PTCS can identify a specific type of biliary tumor preoperatively: mucus-secreting intrahepatic cholangiocarcinoma. Percutaneous hepatic percutaneous portal venography (PTP) in patients with hilar cholangiocarcinoma allows precise preoperative assessment of the degree and extent of invasion of the portal vein bifurcation [3]. Combined hepatobiliary and portal vein resection can result in a significantly longer survival time for patients with advanced hilar cholangiocarcinoma with partial portal vein invasion.