Cholangioscopy is similar to gastroscopy and enteroscopy, it is a technique to enter the cavity for diagnosis, examination and treatment, choledochoscopy is an endoscopic system to examine the biliary system. There are hard and soft choledochoscopes. The so-called hard choledochoscopes are similar to laparoscopes, cystoscopes, and hysteroscopes, but the biliary tract is structurally complex, so that simple hard choledochoscopes can not reach the target, and can be examined by soft choledochoscopes. There are several aspects of cholangioscopy access, because the bile duct normally passes through the duodenal papilla and duodenum, so cholangioscopy is mostly performed during surgery, through the common bile duct into the intrahepatic bile duct, down into the lower part of the common bile duct, to check for stones, tumors, and stenosis; and there is also a cholangioscopy method of percutaneous transhepatic cholangioscopy, which is based on the PTCD and goes into the intrahepatic and extrahepatic bile ducts. The cholangioscopic technique is a percutaneous transhepatic cholangioscopic technique. Cholangioscopy is needed when there is a possibility of bile duct stones, stenosis, or tumors inside or outside of the liver, and especially when determining whether the patient’s bile ducts inside or outside of the liver are diseased during surgery.