The　R-curve　of　Al2O3/BN　ceramic　composites　was　evaluated　by　the　indentation　strength　method　and　compared　with　the　R-curve　of　monolithic　Al2O3.　The　results　indicate　that　the　Al2O3/BN　ceramic　composites　possess　rising　R-curve　behavior,　which　exhibit　an　excellent　crack　growth　resistance.　The　monolithic　Al2O3　shows　a　plateau　R-curve　behavior.　The　considerable　improvement　of　crack　growth　resistance　is　closely　related　with　h-BN　super　fine　particulates　toughening　mechanism,　which　is　chiefly　attributed　to　the　microcracks　in　the　weak　layer　structure　of　h-BN　caused　by　the　elastic　modulus　and　thermal　expansion　mismatch　between　Al2O3　and　BN.