Ultrafine WC-Co-VC cemented carbides are used extensively in a variety of industrial environments for their excellent mechanical properties and outstanding wear resistance.Co content affects the service performance of the cemented carbides.In the present study, the influence of Co content on microstructure, physical and mechanical properties was investigated systematically.Ultrafine WC-Co-VC cemented carbides with varying Co content from 4.0 to 7.0wt% and assistance of VC (0.35wt.%) as inhibitor of WC grain growth were prepared.The physical and mechanical properties were tested and the microstructure characteristics were observed using metalloscope and SEM.From the results, it was found that with Co content increasing, both the cobalt magnetism and bending strength increased, while the coercive force, Rockwell hardness, density and abrasive wear resistance decreased.In addition, the metalloscope and SEM results showed that the increase of Co content in WC-Co-VC cemented carbides tended to reduce the quentity and size of micro-pores, and make the change of fracture mode from brittle fracture to ductile fracture.