Very　recently,　high　entropy　concept　has　evolved　from　metal　to　the　ceramic　community,　named　as　high　entropy　ceramics　(HEC).　The　configurational　entropy　endowed　the　system　with　unique　structure,　performances　as　well　as　application　potentials　such　as　aerospace,　high-speed　machining　tools,　and　nuclear　reactors.　However,　the　poor　densification　together　with　low　fracture　toughness　of　HEC　significantly　limited　the　practical　applications　of　HEC.　Herein,　we　report　for　the　first　time　the　employment　of　low-dimensional　nanomaterials　including　multilayer　graphene　(MLG),　carbon　nanotube　(CNT)　and　SiC　nanowire　(SiCnw)　to　improve　the　densification　coupled　with　fracture　toughness　of　HEC　through　two-step　spark　plasms　sintering.　HEC-MLG　and　HEC-SiCnw　exhibited　flexural　strength　of　671.3　MPa　and　626.5　MPa,　with　fracture　toughness　of　7.1　MPa　m1/2　and　6.2　MPa　m1/2,　respectively.　The　strength　and　toughness　of　HEC　nanocomposites　were　both　greater　than　those　of　the　reported　values　for　high　entropy　ceramics.　The　reinforcing　mechanisms　were　discussed　in　detail　for　all　the　three　HEC　nanocomposites.　Overall,　this　paper　demonstrated　that　the　toughening　methods　for　normal　ceramics　were　also　feasible　for　HEC　matrix,　significantly　increasing　the　freedom　to　tailor　the　properties　and　applications　of　HEC.　©　2021　Elsevier　Ltd