• 18-75 years old.

• Histopathologically confirmed patient with an inoperable metastatic colorectal adenocarcinoma.

• The unresectable stage of metastatic disease has not received any systemic antitumor therapy.

• For subjects previously receiving neoadjuvant or adjuvant therapy, the date of first discovery of disease progression must be at least 12 months removed from the date of last administration of neoadjuvant or adjuvant therapy.

• The presence of at least 1 measurable lesion that can be evaluated according to the RECIST v1.1 criteria.

• ECOG 0

• Normal bone marrow and organ function: ① Neutrophils (ANC) ≥1.5×10\^9/L, platelets (PLT) ≥100×10\^9/L, hemoglobin (Hb) ≥90g/L, white blood cells (WBC) ≥3.0×10\^9/L, albumin (ALB) ≥35 g/L, and no bleeding tendency; ② AST, ALT and alkaline phosphatase (ALP) were all ≤2.5× upper limit of normal range (ULN), and ≤5×ULN when liver metastases occurred; The total bilirubin level doesn't exceed the upper limit of the agency's normal range; Serum creatinine (Cr) ≤1.5×ULN or creatinine clearance ≥60 ml/min (calculated according to Cockroft-Gault)

• Understand the situation of this study, patients and/or legal representatives voluntarily agree to participate in this study and sign informed consent form.