Fecal occult blood test may be positive. Carcinoembryonic antigen (CEA) and glycocalyx antigen CA-199, CA-50, CA-242 in serum and bile have certain positive rate in cholangiocarcinoma, which can be used for auxiliary diagnosis and postoperative follow-up. 1. Increased direct bilirubin: Laboratory examination shows obstructive jaundice, and elevated serum total bilirubin and direct bilirubin shows cholestatic jaundice. 2.Secondary liver damage: in long-term biliary obstruction, there may be secondary liver function damage, ALT and AST mildly elevated is the manifestation of secondary liver damage. Mild elevation of ALT and AST is a manifestation of secondary liver damage. Decrease in total serum protein and albumin is a manifestation of malnutrition and liver damage. Prolonged prothrombin time is a sign of biliary obstruction and secondary liver damage. γ-GT and alkaline phosphatase are increased. ALP and γ-GT are elevated in the early stage without jaundice, suggesting bile duct obstruction. 3.Blood test: more than half of the patients have blood leukocyte count above 8×109/L, if it is obviously elevated, it suggests biliary tract infection. 61%～70% of the patients may have different degrees of Hb reduction. The main purpose of imaging is to diagnose the site of obstruction, determine the nature of possible lesions and estimate the scope of the lesion and the relationship with the surrounding tissues and organs. 4, B ultrasound: Among the many imaging tests, B ultrasound is the preferred diagnostic method. Real-time ultrasound has a high diagnostic rate for the location and degree of bile duct obstruction, and the detection rate of bile duct dilatation can reach more than 95%, which is the preferred examination. Ultrasound-guided fine-needle aspiration cytology is a simple, safe and effective method. The probe of endoscopic ultrasound (EUS) is separated from the biliary system by only one layer of intestinal wall, which excludes the interference of overlapping chest and abdominal walls and gastrointestinal tract, and allows clearer observation of the biliary tract. Intraductal-ultrasonography (IDUS) utilizes a miniature ultrasound probe, which can directly enter the bile duct via the PTC sinus tract or ERCP route to scan the bile duct, completely eliminating the interference of covering bile duct tissues, and the image is clearer than that of EUS. IDUS can detect small bile duct cancers, and the accuracy of the judgment of the depth of infiltration of bile duct cancers is 73%, and it is also useful for the determination of whether the pancreas and duodenum are infiltrated with bile duct cancer. The accuracy of judgment of whether the pancreas and duodenum are involved is 100%. The further use of endoluminal color Doppler ultrasound (ECDUS) can detect blood flow in the vessels surrounding the biliary system, and is 100% accurate in determining whether the hepatic artery and portal vein have been invaded.