ERCP: Transendoscopic retrograde cholangiopancreatography is a contrast technique that applies an electronic duodenoscope and related instruments to insert and inject contrast medium through the mouth to the duodenal papilla, thus retrogradely displaying the pancreaticobiliary duct, which is currently recognized as the gold standard for the diagnosis of pancreaticobiliary duct disease. On the basis of ERCP, interventions such as duodenal papillary sphincterotomy (EST), stone extraction, endoscopic nasal bile drainage (ENBD) and biliary stent placement (ERBD) can be performed, which are widely used for the minimally invasive endoscopic treatment of biliary stones and biliopancreatic tumors. ERCP is a minimally invasive procedure that requires no incision, is minimally invasive, has a quick recovery, and does not change the original anatomy of the body and does not affect the subsequent treatment; the hospital stay is short; and it is more advantageous for patients who do not have the conditions for open surgery, especially the elderly. The main indications for ERCP: 1. bile duct stones: duodenoscopic removal of stones can replace traditional dissection and T-tube drainage, which is less traumatic and can prevent stone recurrence; 2. bile duct residual stones after cholecystectomy: endoscopic stone removal to avoid reoperation; 3. acute biliary severe pancreatitis: early endoscopic nasobiliary drainage can improve the success rate of treatment; 4. chronic pancreatitis and pancreatic duct stones; 5. 5. obstructive jaundice caused by bile duct cancer or pancreatic head cancer: endoscopic placement of stent is feasible to relieve jaundice, delay liver failure and prolong survival.