• Provide written informed consent to participate in the study voluntarily.

• Male or female aged 18-75.

• Metastatic colorectal adenocarcinoma confirmed by histology or cytology.

• Have not received systematic anti-tumor therapy before; Patients who have received neoadjuvant/adjuvant therapy may be screened from the time of last chemotherapy to recurrence or progression more than 6 months.

• RAS/BRAF mutation status and UGT1A1\*28/\*6 gene polymorphism typing should be determined before enrollment.

• The ECOG PS score is 0 or 1.

• Life expectancy is at least 3 months.

• According to RECIST 1.1, the investigators evaluated that there were measurable lesions at baseline (according to RECIST 1.1), which could be measured if they had not received local treatment such as radiotherapy (lesions located within the area of previous radiotherapy could also be selected as target lesions if progression was confirmed).

• The function of vital organs meets the following requirements (no blood component, cell growth factor correction therapy drugs are allowed within 14 days before the first use of the study drug);

∙ Absolute neutrophil count (ANC) ≥1.5×109/L

‣ Platelet ≥100×109/L;

‣ Hemoglobin ≥9g/dL;

‣ Serum albumin ≥2.5g/dL;

‣ Total bilirubin ≤1.5 × ULN; ALT and AST≤2.5 × ULN, if there is liver metastasis, ALT and AST≤5 × ULN;

‣ Serum creatinine ≤1.5 × ULN or creatinine clearance \> 60 mL/min (Cockcroft-Gault);

‣ Activated partial thromboplastin time (APTT) and International Normalized ratio (INR) ≤1.5 × ULN (for stable dose anticoagulant therapy such as low molecular weight heparin or warfarin and INR within the intended therapeutic range of anticoagulants can be screened)

⁃ Fertile female subjects are required to have a negative serum pregnancy test within 72 hours before the first dosing, are not breastfeeding, and use effective contraception (such as Iuds, contraceptives, or condoms) during the trial period and for at least 6 months after the last dosing of the study drug; Male subjects whose partner is a fertile woman should be surgically sterilized or agree to use effective contraception during the trial period and within 3 months after the last dose of the study drug. Sperm donation is not allowed during the study period;