Boron　nitride　(BN)　as　an　emerging　and　revolutionary　metal-free　catalyst　has　demonstrated　great　potential　in　various　oxidative　dehydrogenation　reactions.　However,　traditional　BN　sheets　always　present　low　catalytic　performance　because　of　the　lack　of　exposed　surface-active　sites.　In　this　work,　we　synthesized　a　three-dimensional　(3D)　porous　fiber-like　BN　material　via　self-assembly　of　boric　acid　and　melamine.　In　the　catalytic　oxidative　dehydrogenation　of　propane　(ODHP),　the　as-synthesized　BN　showed　remarkable　selectivity　to　propylene　(76.4%),　and　the　selectivity　to　alkenes　was　above　90%　at　a　16.4%　conversion　of　propane,　while　the　selectivity　to　undesired　CO2　was　negligible.　Meanwhile,　the　3D　BN　also　exhibited　excellent　catalytic　stability　up　to　200　h　at　520　°C,　which　was　much　better　than　traditional　BN　sheets.　Mechanistic　insight　into　the　formation　process　of　3D　porous　BN　fibers　suggests　the　key　role　of　surface　BOX　affiliated　to　BN　for　stable　3D　structure　in　contributing　to　the　high　catalytic　activity　and　outstanding　stability.　This　work　is,　therefore,　a　blueprint　for　the　construction　of　the　next-generation　BN　catalyst　for　a　highly　efficient　ODHP.　©　2021　American　Chemical　Society.