Indications 1.Biliary obstruction due to malignant tumors (primary or metastatic) can be used both as preoperative preparation and as palliative treatment for patients with advanced tumors. 2, Bile duct stones with the following conditions: elderly or other surgical risks, not suitable for surgery; not suitable for EST or unsuccessful endoscopic stone extraction; prevention of stone impaction or cholangitis attack, can be used as preoperative preparation. 3, benign biliary stricture, can be applied after endoscopic dilation. 4, Sclerosing cholangitis. 5.Biliary fistula. Preoperative preparation 1. Instrument preparation (1) Endoscopy: therapeutic fiber or electronic duodenoscope with a biopsy orifice diameter of 3.2 mm or more. (2) ERCP contrast attachment. (3) Guidance wire: same as ENBD. (4) Bile duct dilatation balloon. (5) Bile duct internal drainage stent. (6) Pusher: choose the pusher matching with the endobiliary stent, of which the 7-8.5 Fr stent pusher is only the same caliber pushing cannula, and the pusher of the stent above 10 F needs 5-7 F internal guide tube in addition to the same caliber pusher as the stent. 2. Patient preparation: same as ENBD. Operation method 1. Routinely perform ERCP to understand the site and scope of biliary lesion. 2.Determine the site of stent drainage and placement of stent. (1) For common bile duct obstruction, after imaging, insert the guiding wire and pass through the stenosis, then keep the guiding wire unchanged, insert the stent and the corresponding pusher according to the guiding wire, and gradually send the stent into the bile duct by relying on the power of the bending angle knob and the lifter, while the end of the stent below the barb is left outside the duodenal papilla, hold the stent with the pusher and pull out the guiding wire, and bile can be seen to spill out smoothly. Finally, the pusher and endoscope were withdrawn in turn, and the patient was supine to take X-ray of the liver area to understand the position of the stent. (2) For hilar obstruction, the stent is usually placed in the right intrahepatic bile duct to drain most of the bile; if possible, one stent is placed in each of the left and right hepatic ducts for better drainage effect. The specific operation: first pass a guide wire through the stenosis and into one hepatic duct, then insert a guide wire into the other hepatic duct, and finally place the stent along the guide wire respectively. (3) If used for drainage of common bile duct stones, the stent should be inserted along the guidewire with the distal end 1-2 cm beyond the stone and ending outside the duodenal papilla.