Abstract: In order to improve the wear resistance of the clad layer, the powder mixture of stellite-6 and tungsten carbide (WC) in the range of 0~0.47 mass fraction of WC was deposited on mild steel plates by CO2 laser cladding system. The phase constitution, microstructure, hardness and wear resistance of the clad layer were studied with an X-ray diffractometer, energy dispersive spectroscopy, scanning electron microscope, laser microscope, Vickers hardness tester and wear tester. According to the analyzed results, the microstructure of the clad layer consists of hypoeutectic structure and undissolved tungsten carbides dispersed in the matrix of the Co-based alloy. The Vickers hardness increases with the increase of WC weight fraction. On the other hand, the crack sensitivity of the laser clad layer is low.