It is a trial to compare the efficacy and safety of Nab-paclitaxel plus Cisplatin vs Gemcitabine plus Cispatin as first line chemotherapy in advanced biliary tract cancer.

Inclusion Criteria:

1. Aged 18 to 70 years;
2. Diagnosis of unresectable or recurrent or metastatic biliary tract cancer (Ampulla of Vater, gallbladder, intra or extra-hepatic biliary ducts);
3. Adequate bone marrow, liver and kidney function: absdute neutrophil count (ANC) ≥ 1.5 x 10^9/L, platelet count (PLT) ≥75 x 10^9/L, hemoglobin (HB) ≥ 75 g/L, White blood cell(WBC) ≥ 3.0 x 10^9/L, no bleeding symptoms or bleeding tendency; Total bilirubin (TBIL) ≤ 3 x upper limit of normal range (ULN), alanine glutamate transaminase (ALT) and glutamate transaminase (AST) ≤ 5 x upper limit of normal range (ULN); creatinine(Cr) ≤ 1.5 x upper limit of normal range(ULN) or creatinine clearance rate（CCR）≥ 45ml/min;
4. At least one measurable lesion;
5. Karnofsky Performance Status(KPS) ≥ 70;
6. Estimated life expectancy of at least 3 months;
7. Resolution of all acute clinical toxic effects of any prior treatment to grade ≤ 1, with the exception of alopecia;
8. Be able to understand and willingness to sign IRB-approved informed consent; (If the patient cannot sign the informed consent due to consciousness disorder, upper limbs paralysis or inability to write, the legal representative shall sign the informed consent on behalf of the patient).

Exclusion Criteria:

1. Ongoing uncontrolled infections, or have received systemic antibiotic therapy within 72 hours prior to registration;
2. Myeloproliferative disorder or any other hematopoietic function disorder;
3. Have an untreated second malignancy or brain metastasis;
4. Allergic to the chemotherapy drugs of this protocol;
5. Unable to cooperate due to neurologic diseases or psychiatric illness;
6. Pregnant or lactating female patients; Women of child-bearing age who refuse to accept contraceptive measures;
7. Have other significant medical illness, for example,active tuberculosis, active pneumonia, uncorrected electrolyte disturbance, uncontrolled tumor associated pain, uncontrolled hydrothorax or seroperitoneum and so on;
8. Patients need to receive other antitumor therapy at the same time;
9. Have received any other experimental treatment or participated in another interventional clinical trial within 30 days prior to registration;
10. Any other situation that the researcher considered patients are unsuitable for the trial.