1. General preparation: Systematic laboratory and imaging examinations, understanding of the systemic condition, supplementation of physiologically required water and electrolytes, etc., and preoperative and intraoperative use of antibacterial drugs. Preoperative cardiopulmonary function must be confirmed to be able to tolerate surgery, and mild cardiopulmonary dysfunction should be corrected preoperatively. Coagulation dysfunction should also be corrected preoperatively as much as possible. 2. Liver preservation therapy: For patients with prolonged and severe jaundice, especially those who may undergo extensive hepatic, biliary and pancreatic resection, preoperative assessment of liver function and liver preservation therapy are very important. Some lesions with localized conditions that are still resectable are overwhelmed by the inadequate reserve state of the liver and the opportunity for surgery is lost. Patients with adequate preoperative preparation, some with complex, long and extensive surgeries, can still pass through the perioperative period smoothly. Preoperative preparation is a prerequisite to ensure the safety of surgical performance and to reduce complications and morbidity and mortality rates. The following conditions indicate poor liver function and contraindication to combined liver surgery, especially contraindication to hepatic or pancreatic resection of more than half of the liver: A. Total serum bilirubin above 256 μmol/L; B. Human albumin below 35 g/L; C. Prothrombin activity below 60%, time prolongation greater than 6s, and difficult to correct after 1 week of vitamin K injection. ④ Indocyanine green contour test (indigocyanogreentest) was abnormal. Preoperative CT was applied to measure the volume of the whole liver and the volume of the liver to be resected, and calculate the volume of the preserved liver, which can help to assess liver function in the proposed radical resection of enlarged hilar cholangiocarcinoma. In addition, glucose tolerance test and prealbumin (preprotein) measurement are helpful for estimation of liver function of patients. Preoperative hepatoprotective therapy is necessary, but if biliary obstruction cannot be released, relying on pharmacological hepatoprotective therapy alone is not effective. Currently, commonly used drugs aim to lower transaminases, replenish energy, and increase nutrition. Hypertonic glucose, human albumin, branched-chain amino acids, glucuronolactone (glucuronide), pantodecalinone (coenzyme Q10), vitamin K, and high-dose vitamin C are commonly used. Pre-operative hepatoprotective treatment should also pay attention to avoid the use of drugs that are damaging to the liver. 3. Nutritional support: Preoperative administration of appropriate nutritional support can improve the nutritional status of patients and reduce postoperative complications. Studies have shown that parenteral nutrition can increase the total number of lymphocytes, improve the immune mechanism, defend against infection and promote wound healing. It is now recognized that perioperative nutritional support has a positive effect on reducing complication rates and surgical mortality and promoting patient recovery. For general patients, peripheral intravenous nutrition can be used; for severe patients or those who are expected to have a larger surgery, a deep venous infusion line can be left in place 5-7 days before surgery. For nutritional support in patients with mild liver damage, the caloric supply should be 2000-2500kcal/d and protein 1.0-1.5g/(kg-d). Sugar accounts for 60% to 70% of non-protein calories and fat accounts for 30% to 40%. When blood sugar is high, exogenous insulin can be given. In patients with cirrhosis, the calorie supply is 1500-2000kcal/d. In the absence of hepatic encephalopathy, the protein dosage is 1.0-1.5g/(kg-d); in the presence of hepatic encephalopathy, the protein dosage should be limited to 30-40g/d according to the condition. 37%-50% of branched-chain amino acids can be given to provide energy and increase the ratio of branched-chain amino acids to aromatic amino acids in the blood. To achieve the dual purpose of nutritional support and treatment of liver disease. The dosage of branched-chain amino acids is 1g/(kg-d) and fat is 0.5-1.0g/(kg-d). In addition, adequate vitamins and trace elements must be supplied. For patients with obstructive jaundice, the caloric supply should be 25-30kcal/(kg-d), sugar 4-5g/(kg-d), protein 1.5-2.0g/(kg-d), and fat 0.5-1.0g/(kg-d) restricted. The fat preparation given is a mixture of medium-chain fat and long-chain fat. Adequate vitamins, especially fat-soluble vitamins, must be given. If serum bilirubin >256 μmol/L, bile drainage is feasible to complement the nutritional support. 4, reduction of yellowing treatment: There is still a debate on preoperative reduction of yellowing and drainage. The reasons for not advocating reduction of yellowing are: A. the morbidity and mortality rate and complication rate after reduction of yellowing are not reduced; B. preoperative transendoscopic nasobiliary drainage (ENBD) is difficult to succeed; C. preoperative percutaneous hepatic puncture external biliary drainage (PTCD) complications, especially the threat of embedded biliary tract infection is high. The reasons for advocating yellow reduction are: A. Expanded radical resection requires good preoperative preparation, and yellow reduction is necessary; B. Preoperative decompression for 3 weeks is better than 1 or 2 weeks; C. There is significant improvement in endothelial system function and coagulation; D. At the cellular level, such as prostaglandin-like metabolism are beneficial to alleviate liver damage; E. It is beneficial to the safety of large liver resection. In China, generally for cases with total serum bilirubin higher than 256 μmol/L, yellowing reduction and drainage are mostly taken before planning to perform major radical surgery or large hepatectomy. It is generally believed that for heavy jaundice, long duration (more than 1 month), poor liver function, and the need for major surgical treatment, it is beneficial and necessary to reduce and drain the yellowing first. If drainage is effective in reducing yellowing, but the systemic condition does not improve significantly and liver function does not recover satisfactorily, the choice to perform major surgery should be made carefully. Some people abroad have used interventional embolization of the portal vein stem on the diseased side while reducing yellowing successfully to promote hepatic atrophy on the diseased side and hyperplasia on the healthy side, which not only facilitates surgery but also helps to reduce complications of poor hepatic compensation after surgery and can be used as a reference. 5.Judging the possibility of lesion resection: It is an important part in the preoperative preparation of hilar cholangiocarcinoma, which is helpful to formulate feasible surgical plan and reduce blindness. It is mainly based on imaging examination, but it is very difficult to achieve accurate judgment before surgery, and sometimes it needs to be confirmed after abdominal dissection, so the mutual complement of multiple examination modalities should be emphasized.