Different content of Cu has been loaded onto CoFe2O4 support, and their gas-phase CO oxidation performance has been tested to explore the best Cu loading content and the mechanism of catalyst oxidation. The fundamental characteristics of Cu doped CoFe2O4 are revealed by XRD and TEM. The catalytic mechanism is elucidated by XPS, H-2-TPR, CO-TPD and in-situ DRIFTS. The CO oxidation performance is greatly improved upon Cu doping on the surface of CoFe2O4 catalysts. It is found that 5wt% Cu/CoFe2O4 catalysts showed higher CO oxidation performance. [GRAPHICS] .