Choledocholithiasis is a common and frequent disease in China. In the past, the main treatment for choledocholithiasis in hospitals was surgery: open or laparoscopic choledochotomy, which required a T-tube in the abdomen for a long time (3 weeks to 3 months, or even longer) and a long hospital stay, causing inconvenience in life and work. With the promotion of new technology, there is a good way to treat common bile duct stones: ERCP (endoscopic retrograde cholangiopancreatography), which uses a duodenoscope to perform bile and pancreatic duct imaging, stone extraction and drainage through the opening of the duodenal papilla, and has a huge irreplaceable role in the diagnosis and treatment of biliary and pancreatic system diseases. Clinical application of ERCP in pancreaticobiliary diseases Diagnosis ERCP has a huge role in the diagnosis of biliopancreatic diseases because the biliopancreatic duct confluence is a very precise tissue structure, and ultrasound, CT and other instruments in the biliopancreatic region can see large lesions, but more delicate structures or small lesions are not enough. However, ECRP can directly diagnose the lesions and patency of the pancreaticobiliary duct under the contrast of contrast agent, and therefore has become the “gold standard” for diagnosing pancreaticobiliary duct diseases. Treatment of common bile duct stones ERCP removes stones from the bile ducts through duodenoscopy, which has the advantages of no incision, less pain and fewer complications for the patient, while maintaining the integrity and physiological function of the bile duct system, and the success rate of ERCP papillary sphincterotomy in the hands of experts is greater than 90%. Removal of stones is usually chosen from balloons or mesh baskets, and mechanical lithotripsy can be chosen for large stones or tonal stones, which are more difficult to remove. If stone extraction is unsuccessful, a biliary stent or nasobiliary drainage tube can be placed to drain the stone. Treatment of biliary stricture ERCP is feasible for endoscopic dilatation and stent drainage treatment to release the obstruction and provide effective drainage in time. Bile duct stenosis due to tumor compression will reduce the patient’s quality of life, at this time, placement of bile duct stent under ERCP usually to drain bile is a good choice. Treatment of chronic pancreatitis, pancreatic fistula, and pancreatic cysts ERCP performs pancreatic ductography and is feasible for the microscopic treatment of symptomatic pancreatic duct stones, pancreatic stenosis and pseudocysts. Pancreatic duct stenosis can be effectively treated by dilation and stenting, and endoscopic treatment is preferred for patients with chronic obstructive pancreatitis with abdominal pain; pancreatic duct stenting has become a common treatment for pancreatic fistula. Most severe pancreatic duct injuries can be treated by placing bridge-like stents to re-establish normal pancreatic duct drainage; ERCP can be used to diagnose and treat pancreatic fluid accumulation, including acute pseudocysts, chronic pseudocysts and pancreatic necrosis. After ERCP, only 6-12 hours of fasting is required routinely, and blood amylase will be drawn 2 hours after the examination and the following morning, respectively, and dietary adjustment will be made according to the situation (abdominal signs, presence of complications, blood and urine amylase situation). As science cannot just introduce the advantages without talking about the risks, ERCP, as a highly technical endoscopic operation, also has obvious limitations. First of all, the success rate of its operation is about 90%, and a small percentage of patients will fail the examination operation due to various objective constraints. In addition, ERCP is still an invasive test compared to general ultrasound and CT, and the risks are much greater, with complications including acute pancreatitis and bleeding. Therefore, not all technical work can be done anywhere, it is best to go to an experienced center for treatment, which has seen more and has more experience in dealing with and preventing complications, which is more secure. In conclusion, ERCP has the advantages of no incision, does not necessarily require general anesthesia, less trauma, shorter operation time, shorter hospital stay, faster recovery, fewer complications than surgery, etc. In just a few decades ERCP has made great clinical achievements in biliary and pancreatic diseases and has become an important tool in the diagnosis and treatment of pancreatic and biliary diseases today.