Abstract: The WC-17Co coating was fabricated by supersonic plasma spraying with the low-cost working gas composed of air and propane. The effect of spraying power on the microstructure, porosity and phase composition were investigated. The spraying power showed significant influence on the melting and decarburization behaviors of powder. A low spraying power corresponded to a low melting rate and small decarbonization of WC powder, while an excessive high power would cause serious decarburization with decomposition products of W₂C or even W. A coating with the lowest porosity (0.87%) was sprayed at a power of 65 kW, without the formation of W phase. The coating had strong compressive resistance and anti-deformability, whose wear loss was 15% of the base metal. Because of the high-hardness WC particles, wear resistance of WC-Co coating has been significantly improved. The wear behavior was changed from severe abrasion and adhesive wear of base metal into slight abrasion wear of WC-Co coating.