Abstract: TiB2-TiC ceramic matrix composites were fabricated byin situsynthesis under hot isostatic pressing (HIP) with 3TiH2-B4C and 11TiH2-3B4C being the rawmaterials, respectively. The XRD analysis indicates that the samples synthesized from3TiH2-B4C haveTiB2andTiC phases, while those from11TiH2- 3B4C have notonlyTiB2andTiC phases, but alsoTi3B4phase. SEMresults showthatthe microstructures of the composites synthesized from 3TiH2-B4C are not well-distributed, and there are some platelet grains in some zones, while those from 11TiH2-3B4C are fine with many regular-platelet grains. TiB2-TiCxceramic matrix composites obtained from11TiH2-3B4Chave bettermechanical properties than those from3TiH2-B4C.