Si3N4/BN　composites　were　fabricated　by　spark　plasma　sintering　(SPS)　through　traditional　powder　mixing　process　and　by　a　chemical　route　to　Si3N4/BN　composite　powder,　respectively.　The　SPS-processed　Si3N4/BN　composites　maintain　a　considerably　high　bending　strength,　exhibiting　some　gradual　decrease　though　with　increasing　BN　content.　Given　the　BN　content,　the　bending　strength　is　enhanced　for　the　composites　prepared　by　powder　mixing　relative　to　the　chemical　route　counterparts.　Differences　in　the　alpha　-＞beta　phase　transformation　of　Si3N4　and　grain　growth　during　the　SPS　process　play　a　key　role　in　the　variation　of　strength.　Regardless　of　the　preparation　method,　the　Si3N4/BN　composites　with　a　BN　content　up　to　30　vol.%　can　be　well　machined　with　WC　tools.　(C)　2007　Elsevier　B.V.　All　rights　reserved.