For patients with obstructive jaundice caused by malignant tumors such as cholangiocarcinoma and periampullary carcinoma, most of them are already at an advanced stage when detected, and even in the early and middle stages, a significant number of patients cannot be operated due to their age and the combination of other organ disorders, etc. At this time, endoscopic placement of biliary stents becomes the best treatment option. The key to ERCP is to insert a guidewire through the duodenal papilla and then place an endobiliary stent under the guidance of the guidewire through the biliary stricture caused by tumor. However, in a significant number of patients, the biliary stent cannot be placed because of unsuccessful papillary cannulation due to duodenal diverticulum, narrow papillary opening, excessive curvature of the jugular abdomen, tumor obstruction, and papillary inflammatory edema. In the past, there were only two options for such patients: first, external drainage by PTCD, but patients with external drainage by PTCD have the disadvantages of inconvenient tube carrying, biliary tract infection, and external drainage of bile easily leading to disorder of the internal environment and decreased digestive and absorption function; second, open surgery for internal drainage of bile duct jejunum, but patients need to endure the pain of opening, and some patients cannot tolerate the surgery. The key to this technique is: first, the drainage tube should be placed into the hepatic duct or even the common bile duct during PTCD; and the biliary stent should be placed through the guidewire placed through PTCD during ERCP. The procedure is first performed under ultrasound guidance for PTCD, the puncture point should be close to the hilar during PTCD (close to the hilar is prone to complications such as bile leak), the PTCD drainage tube should be placed in the direction of the common bile duct and as far as possible to the lower part of the common bile duct. there is a drainage tube for the intrahepatic bile duct after PTCD. When placing the stent, a guidewire is placed first through the PTCD tube through the liver and intrahepatic bile duct percutaneously and then into the common bile duct, and then through the bile duct stricture and duodenal papilla into the duodenum.