This is a randomized, double-blind, placebo-controlled, multicenter Phase III clinical trial to compare the efficacy and safety of Fruquintinib plus BSC versus placebo plus BSC in patients with metastatic colorectal cancer who have progressed after second-line or above standard chemotherapy. After checking eligibility criteria, subjects will be randomized into Fruquintinib plus BSC group (treatment group) or placebo plus BSC group (control group) in a ration of 2:1. Primary Efficacy Endpoint: Overall Survival (OS). Secondary Efficacy Endpoints: Progression free survival (PFS) (According to RECIST Version 1.1), Objective Response Rate (ORR), Disease Control Rate (DCR), . Safety and tolerance will be evaluated by incidence, severity and outcomes of AEs and categorized by severity in accordance with the NCI CTC AE Version 4.0.