Abstract: The abrasive wear behavior of WC/Co hardmetals with different hardness and WC grain sizes was comparatively investigated on a ball cratering test rig and steel wheel wet slurry test rig. The worn surfaces of the hardmetals were observed with a scanning electron microscope, in an attempt to explore the abrasive wear mechanism of the hardmetals. As the results, the wear resistance of WC/Co in steel wheel wet slurry test increases considerably with an increase in the hardness. However, in the ball cratering test when the abrasive particle sizes and the grain size of WC in the hardmetals take the same order of magnitude, the abrasive wear resistance of the hardmetals is not regularly related to the hardness but to the gain size of WC grains. Namely, the larger the size of WC grains, the better the abrasive wear resistance of WC/Co hardmetals. SEM observation of the worn surfaces of the hardmetals after ball cratering test indicates that the dominant abrasive wear mechanisms are the cracking and spalling of WC grains. Thus in this case the resistance to spalling of WC grains plays a key role in governing the abrasive wear behavior of the hardmetals.