Abstract: SiC whisker reinforced multilayered Si₃N₄ composites with BN as separating layers were fabricated by compacting rolling, coating, laminating and hotpressing. Si₃N₄ was added into the separating layers to modify interfacical bonding between the matrix layers. With the increase of Si₃N₄ content in the separating layers, the bonding between the matrix layers changed from very weak to tight interface and the bulk mechanical properties varied accordingly. For weak interfaces, the composite exhibits very high apparent toughness up to 20 MPam1/2 with a moderate strength of about 600 MPa, while for tight interface, the composite fractures behave like monoliths and give a high strength of over 1000 MPa.