• Sign the informed consent form voluntarily and follow the protocol requirements;

• Gender is not limited;

• Age ≥18 years old and ≤75 years old;

• Expected survival time ≥3 months;

• Patients with advanced biliary tract cancer confirmed by histology or cytology;

• Patients must provide a documented tumor tissue specimen of the primary or metastatic tumor within 3 years for PD-L1 testing and other testing;

• At least one measurable lesion meeting the RECIST v1.1 definition was required;

• ECOG score 0-1;

• The toxicity of previous antineoplastic therapy has returned to ≤ grade 1 as defined by NCI-CTCAE v5.0;

⁃ No severe cardiac dysfunction, left ventricular ejection fraction ≥50%;

⁃ Organ function level must meet the requirements;

⁃ Coagulation function: international normalized ratio (INR) ≤1.5×ULN, and activated partial thromboplastin time (APTT) ≤1.5×ULN;

⁃ Urinary protein ≤2+ or ≤1000mg/24h;

⁃ For premenopausal women of childbearing potential, a pregnancy test must be performed within 7 days before starting treatment, a serum or urine pregnancy test must be negative, and the patient must not be lactating; All enrolled patients should take adequate barrier contraception during the entire treatment cycle and for 6 months after the end of treatment.