Ni-based WC composite coatings conducted on the surface of 45 steels by free spraying followed with high frequency induction remelting were investigated. The influences of induction remelting time on properties of the coating were discussed. The wear resistance of the coating and the elemental diffusion cross the interface between the coatings and the substrate were analyzed. The compositions and microstructure of the coating before and after a wear test were characterized by scanning electron microscope with energy dispersive X-ray microanalysis. The results indicate that a coating which is free from crackers and pores composed of Ni-based solid solution and dispersed tungsten carbide is obtained by free spraying and induction remelting. The interface is a white lamellar zone. The mutual diffusion of iron and nickel in the interface proves it’s an atomic bonding between the substrate and the coating. The wear mechanisms of the coated sample are abrasive wear and microplowing. The wear resistance of Ni-based WC composite coatings is superior to that of quenched high carbon steels.