• 1\. Aged \>= 18 years, male or female; 2. Histologically or Cytologically confirmed metastatic pancreatic adenocarcinoma; 3. Patients have never received systematical anti-cancer therapy; 4. Based on Response Evaluation Criteria In Solid Tumors (RECIST1.1), there should be at least one measurable lesion which has never received local treatment like radiotherapy(The lesion located in previous radiotherapy areas can also be selected as target lesions if the progress confirmed.) 5. ECOG:0-1; 6. Expected survival\>=12 weeks; 7. Essential organs function must meet the following criteria (Any blood products, growth factor, leucocyte promoting drugs, platelet promoting drugs, drugs for anemia are not allowed in 14 days before the first use of the experimental medication):

‣ Absolute neutrophil count(ANC) \>= 1.5x10\^9/L

⁃ Platelet \>= 85x10\^9/L

⁃ Hemoglobin \>= 90g/L

⁃ Serum Albumin \>= 30g/L

⁃ Total bilirubin \<= 2.0 ULN (Biliary obstructive patients after biliary drainage \<= 2.5 ULN), AST and ALT \<= 3.0 ULN (patients with liver metastasis \<= 5 ULN);

⁃ Creatinine clearance rate \>60 mL/min;

⁃ Activated Partial Thromboplastin Time and International Standardized Ratio \<= 1.5 ULN (Patients using stable dose of anticoagulant therapy such as low molecular weight heparin or warfarin and INR is within the expected range of anticoagulants can be selected.)