The　R-curve　behavior　of　SiC/BN　multilayered　ceramics　with　different　components　in　the　weak　layer　was　evaluated　using　the　indentation-strength-in-bending　technique.　The　influence　of　the　components　of　the　weak　layer　on　the　R-curve　of　the　SiC/BN　multilayered　ceramics　was　studied.　The　results　show　that　a　rising　R-curve　behavior　is　demonstrated　for　the　laminated　SiC/BN　ceramics,　and　varies　with　the　components　of　the　weak　layer.　The　SiC/BN　multilayered　ceramic　with　30%　Al2O3　addition　in　the　weak　layer　has　a　steepest　rising　R-curve.　The　above　results　are　attributed　to　their　different　toughening　mechanisms　and　interfacial　coherent　states.　In-situ　toughening　is　the　main　toughening　mechanism　for　the　monolithic　SiC　ceramics,　while　crack　deflection,　crack　branching　and　crack　delami-nating　at　the　SiC/BN　weak　interfaces　for　SiC/BN　multilayered　ceramics.　The　components　in　the　weak　layer　have　an　important　effect　on　the　crack　deflection.　The　interface　with　a　right　coherent　stress　contributes　to　the　crack　deflection,　and　the　interface　with　too　weak　or　very　strong　coherent　stress　does　harm　to　the　crack　deflection.