This is a prospective, multicenter, randomized controlled, phase II study. It is expected to enroll 229 patients and aims to evaluate the efficacy and safety of FOLFOX8 versus mFOLFOX6 combined with bevacizumab or cetuximab as first-line treatment for unresectable metastatic colorectal cancer. The primary objective is to assess progression-free survival (PFS) of the patients. Secondary objectives include assessment of objective response rate (ORR), overall survival (OS), safety, and other outcomes.