Abstract: The changes of morphology and composition of WC particles in the WC particle-reinforced M2 high speed steel composites frabicated by spray forming were studied.The results shows that the morphology and the composition of WC particles have been changed considerably,while the micro-hardness has not been decreased obviously.The hardness of WC particle-reinforced MMCs is appreciably higher than that of the high speed steel made by spray forming,casting or forging process.