Hexagonal　boron　nitride　(h-BN)　ceramics　exhibit　exceptional　thermal　conductivity,　yet　integrating　their　anisotropic　thermal　properties　into　bulk　ceramics　remains　challenging.　This　study　investigates　the　impact　of　bimodal　particle　size　distribution　on　the　structure,　thermal　and　mechanical　properties　of　h-BN　ceramics.　Through　DEM　simulations　and　hot-pressing　techniques,　we　demonstrate　that　incorporating　large　particles　into　fine　ones　significantly　enhances　the　packing　density,　structural　anisotropy　and　thermal　properties　of　h-BN　ceramics.　The　resulting　high-purity　h-BN　ceramic　prepared　with　10　vol%　large　particles　(10LBN)　exhibits　an　Index　of　Orientation　Preference　(IOP)　of　−2780.57,　surpassing　that　of　ceramics　without　large　particles　(0LBN)　at　−1168.61.　By　regulating　the　structure,　10LBN　h-BN　ceramic　show　a　notable　increase　of　the　in-plane　thermal　conductivity　from　81.78　for　0LBN　ceramics　to　153.20　W/(m·K),　along　with　a　flexural　strength　of　58.21　MPa.　Additionally,　structural　characterization　and　performance　testing　show　that,　compared　to　adding　sintering　additives,　incorporating　large　plate-like　h-BN　particles　offers　greater　benefits　in　optimizing　the　orientation　structure　and　thermal　conductivity　of　h-BN　ceramics.　These　findings　offer　new　insights　for　powder　compaction　using　dual-sized　plate-like　particles　and　into　the　sintering　of　h-BN　ceramics　with　tailored　structural　and　thermal　properties.　©　2024　Elsevier　Ltd　and　Techna　Group　S.r.l.