Endoscopy is a new technology in clinical medicine. In recent years, with the development of new gastrointestinal endoscopes and the application of microelectronics, computers and other high technology, the scope of gastrointestinal endoscopy, the ability to distinguish, and the performance of operation have been greatly improved, and various diagnostic and therapeutic techniques under endoscopy have been developed rapidly. Especially, the emergence and wide application of electronic endoscopy, magnifying endoscopy and ultrasonic endoscopy have greatly improved the diagnosis and treatment level of digestive system diseases. Endoscopic treatment techniques, such as endoscopic hemostasis, polypectomy, endoluminal stent placement, papillary sphincterotomy, nasal-biliary drainage, early cancer mucosal resection, and gastric intracavitary folding and suturing, have been widely used in clinical practice, and endoscopic treatment can achieve satisfactory results with less damage, lower cost and fewer complications than surgical procedures. With the development of endoscopic examination and treatment technology, transduodenoscopic retrograde cholangiopancreatography (ERCP) and endoscopic treatment technology combined with ERCP have become important diagnostic and therapeutic means for pancreaticobiliary system diseases. Through duodenal papillary sphincterotomy (EST), most of the common bile duct stones can be removed smoothly, changing surgical treatment into non-surgical treatment, and it can directly do incision and drainage and place internal stents for obstructive jaundice caused by lower bile duct stenosis or periampullary tumor to restore bile-intestinal circulation. It is widely used in the treatment of biliary-pancreatic system diseases such as common bile duct stone, acute biliary pancreatitis, acute cholangitis, end stenosis of common bile duct and peri-potbelly tumor because it has the advantages of no general anesthesia, less trauma, less pain, faster recovery, less cost, less complications, lower mortality rate, and is not limited by adhesions of common bile duct after multiple surgeries and old age and frailty.