Inclusion Criteria:
1. Age: 18-70 years;
2. Primary resectable extrahepatic cholangiocarcinoma proved by pathology which underwent radical surgery;
3. Pathology indicates R0 with N1 or Neurovascular invasion; or R1;
4. ECOG PS 0-1;
5. Adequate hematologic, hepatic and renal function: ANC ≥ 1.5x10\^9/L, Hb ≥ 80g/L, PLT ≥ 100 x10\^9/L, albumin ≥ 28g/L, total bilirubin \< 1.5×ULN, ALT and AST \< 2.5×ULN, CREA\<1.5×ULN;
6. No anti-tumor treatment before radical resection, including radiotherapy and chemotherapy, targeted therapy and immunotherapy；
7. At least 6 months of life expectancy.
Exclusion Criteria:
1. Diagnosis of other malignant diseases outside the biliary tract within 5 years before the first administration (excluding radically cured skin basal cell carcinoma, skin squamous cell carcinoma, and/or radically excised carcinoma in situ);
2. Pregnant or breastfeeding women, or expecting to conceive or father children within the projected duration of the trial;
3. With purulent, infected or delayed healed wounds;
4. Have thromboembolism in the past 6 months, including myocardial infarction, unstable angina, stroke or transient ischemic attack, pulmonary embolism, deep vein thrombosis;
5. An active autoimmune disease that requires systemic treatment (such as the use of disease-relieving drugs, glucocorticoids, or immunosuppressive agents) occurred within 2 years before the first administration. Alternative therapies (such as thyroxine, insulin, or physiological glucocorticoids for adrenal or pituitary insufficiency) are not considered systemic treatments. Known history of primary immunodeficiency. Only patients with positive autoimmune antibodies need to confirm whether there are autoimmune diseases based on the judgment of the investigator;
6. Are receiving systemic glucocorticoid therapy (excluding nasal spray, inhaled or other local glucocorticoids) or any other form of immunosuppressive therapy within 4 weeks before the first administration of the study. Note: Physiological doses of glucocorticoids are allowed (≤10 mg/day prednisone or equivalent drugs);
7. Have other uncontrollable comorbidities;
8. Infection of HIV, known syphilis requiring treatment;
9. Uncontrollable hypertension, systolic pressure\>140mmHg or diastolic pressure\>90mmHg after best medical care, or history of hypertensive crisis or hypertensive encephalopathy;
10. Symptomatic congestive heart failure (NYHA class II-IV). Symptomatic or badly-controlled arrhythmia. Congenital long QT syndrome or modified QTc\>500ms upon screening;
11. Have active autoimmune diseases that require systemic treatment within 2 years before enrolment;
12. Active tuberculosis, having antituberculosis therapy at present or within 1 year;
13. The medical history or disease evidence, abnormal treatment or laboratory test values that may interfere with the test results, prevent the subject from participating in the study, or the investigator believes that it is not suitable for inclusion in the group. The investigator believes that there are other potential risks and is not suitable for participation；
