In the past, the main treatment for common bile duct stones was surgery: open or laparoscopic choledochotomy, after which a T-tube was placed in the abdomen for 2 to 3 months, resulting in long operation time, high complication rate, long hospital stay, high treatment cost, and long-term retention of the T-tube, which caused inconvenience in life and work. In particular, patients with common bile duct stones who have undergone cholecystectomy in the past are often unable to undergo laparoscopic minimally invasive surgery because of the adhesions caused by the original surgery, and another open surgery will cause great physiological trauma to the patients. This often causes great psychological trauma to the patient on top of the physical trauma. In the era of minimally invasive surgical treatment, how to provide minimally invasive and effective treatment to patients with common bile duct stones has become a challenge for hepatobiliary surgeons. ERCP refers to endoscopic retrograde cholangiopancreatography, that is, the use of duodenoscopy, through the opening of the duodenal papilla for the imaging of the bile and pancreatic ducts and other operations to diagnose and treat diseases of the biliary and pancreatic system. ERCP removes stones from the bile ducts through the duodenoscope, and the patient does not need to undergo surgery, which is less painful and has the advantages of safety, effectiveness, simplicity and fewer complications, while maintaining the integrity and physiological function of the biliary system. ERCP in pancreaticobiliary diseases: 1. Common bile duct stones: Common bile duct stones are the most common cause of bile duct obstruction. The clinical manifestations are biliary colic, obstructive jaundice, cholangitis or biliary pancreatitis. the sensitivity and specificity of ERCP in diagnosing common bile duct stones is more than 95%. Currently in expert hands, the success rate of ERCP papillary sphincterotomy for stone extraction is greater than 90%, with an overall complication rate of 5% and a mortality rate of less than 1%, all of which are superior to surgical treatment. In case of failure of selective bile duct cannulation, pre-incision is feasible, but its complication rate is higher than that of conventional methods. In addition to papillary sphincterotomy, balloon dilation of the biliary sphincter is additionally an option. In some special cases, such as those with abnormal coagulation and those at high risk of post-ERC pancreatitis, balloon dilation can be chosen. Removal of stones is usually chosen from balloon or mesh basket, 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 should be placed to drain the stone.2. Benign and malignant biliary strictures: ERCP can be used for the diagnosis and treatment of malignant biliary obstruction, and biopsy, brushing, and ultrasound endoscopy-mediated puncture can provide a histologic diagnosis, but the overall sensitivity is no higher than 62%.ERCP is also used for the diagnosis and treatment of benign biliary obstruction, congenital abnormalities of the biliary tract, and post-surgical complications, including Biliary complications after liver transplantation. Endoscopic dilatation and stent drainage are indicated for bile duct strictures. The placement of biliary stents provides effective drainage for benign and malignant biliary obstruction, with metal stents providing twice the patency time of plastic stents and a better cost-benefit ratio. Metal stents are indicated for patients with a long survival expectancy, no distant metastases and a short opening time with plastic stents. Biliary stents are also helpful in the treatment of postoperative biliary strictures and biliary fistulas.3. Chronic pancreatitis, pancreatic fistulas, pancreatic cysts: ERCP with pancreatic ductography, microscopic treatment of symptomatic pancreatic duct stones, pancreatic duct strictures and pseudocysts is feasible. 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 a bridge-like stent to re-establish normal pancreatic duct drainage; ERCP can be used to diagnose and treat fluid accumulation in the pancreas, including acute pseudocysts, chronic pseudocysts and pancreatic necrosis.