Abstract: The effect of decreasing boride brittleness by pack RE chrome boronizing on its wear resistance and mechanism has been studied using an MM 200 wear tester. The results show that when brittleness drops by 42.8%,the adhesion, abrasion and fatigue wear resistance of the boride layer increases by 26%~60%, 27%~80%, and 86%~116%, respectively. The boride layer of low brittleness shows slight indentation cracks, pillar crystal breaking and shallow stripping under drawing and pressing stress.