Thermal　shock　resistance　of　machinable　Al2O3/BN　nanocomposites,　fabricated　via　chemical　coating　process　and　subsequently　hot-pressing,　was　investigated.　The　experimental　results　revealed　both　thermal　fracture　resistance　and　thermal　damage　resistance　of　the　nanocomposites　were　obviously　improved　in　comparison　with　Al2O3　monolith.　A　temperature　difference　(Δ　Tc)　increase　of　about　100　percent,　from　195°C　for　Al2O3　monolith　to　395°C　for　the　nanocomposites　was　found　in　this　work,　which　was　mainly　attributed　to　the　low　Young＇s　modulus　and　relatively　high　strength　due　to　the　soft　h-BN　addition　and　its　homogegeous　distributions　with　super　fine　grain　size.　Layer-structured　h-BN　can　help　to　relax　stress　and　absorb　energy　through　microcracking,　and　then　prevent　sudden　decrease　of　the　residual　strength　after　thermal　shock.