Biliary stents are used for patients with malignant obstructive biliary tract diseases such as bile duct cancer and pancreatic head cancer. Such patients who are unable to undergo surgery can have biliary stent implantation to improve their quality of life and prolong their survival. There are two types of biliary stent implantation, including endoscopic biliary stent implantation and bile duct puncture with biliary stent placement under radiological intervention. The transendoscopic approach to biliary stent placement is guided by a DSA machine in the interventional operating room, using a duodenoscope to reach the stomach from the mouth through the esophagus to the duodenal papilla, and a plastic stent or a metal stent is placed through the retrograde cannula of the duodenoscope into the bile duct. Placement of biliary stent under radiological intervention is done under DSA machine, through puncture into the bile duct, and under X-ray guidance, the stent is crossed over the tumor stenosis section by a special guide wire to make the stent cross the tumor location for drainage purpose.