AlN-BN　composite　is　considered　to　be　a　promising　material　for　Microwave　transparent　applications.　In　this　paper,　a　series　of　AlN-BN　composites　with　various　content　of　BN　(0　wt%,　5　wt%,　15　wt%　and　30　wt%)　were　prepared　by　spark　plasma　sintering　with　multiple　components　sintering　additives　at　a　low　temperature　(1650　degrees　C),　and　the　effect　of　sintering　conditions　and　composition　on　the　thermal　conductivity　and　high　frequency　dielectric　properties　within　frequency　range　from　10　MHz　to　1.5　GHz　was　investigated.　The　results　show　that　the　spark　plasma　sintering　process　and　the　multiple　components　of　the　sintering　additives　promote　the　densification　of　the　samples.　The　thermal　conductivity　and　dielectric　constant　of　samples　decrease　with　increasing　BN　content,　while　the　variation　of　the　dielectric　loss　depends　on　the　content　of　residual　carbon　and　other　impurities　which　may　result　in　the　relaxation　loss　of　electronic　polarization　and　conductive　loss.