This　study　aims　to　develop　a　highly　sensitive　fire-warning　material　by　synergistically　combining　graphene　oxide　(GO)　with　boron　nitride　(hBN),　renowned　for　its　exceptional　thermal　conductivity　and　flame　retardancy.　Urea　and　water　were　employed　as　precursors　to　exfoliate　and　functionalize　hBN　via　a　semi-solid-state　stone-milling　method,　yielding　amino-functionalized　boron　nitride　nanosheets　(BNNS-NH2)　possessing　a　high　aspect　ratio.　Subsequently,　BNNS-NH2　was　assembled　with　GO　through　a　layer-by-layer　assembly　approach　to　fabricate　a　BNNS/GO　composite　membrane.　Fire-warning　tests　were　conducted　on　the　composite　membrane,　unveiling　an　impressively　short　fire　response　time　of　only　0.2　s　and　an　extended　duration　of　up　to　52　s,　thus　demonstrating　its　exceptional　sensitivity　and　long-lasting　fire-warning　performance.　Upon　exposure　to　fire,　the　GO　layer　within　the　composite　membrane　underwent　thermal　reduction,　leading　to　the　formation　of　electrically　conductive　reduced　graphene　oxide　(RGO).　The　high　thermal　conductivity　of　the　BNNS　layer,　coupled　with　strong　interfacial　bonding,　facilitated　rapid　heat　propagation　throughout　the　composite　membrane,　thereby　promoting　the　thermal　reduction　reaction　of　GO　and　enhancing　the　response　speed.　Furthermore,　the　outstanding　flame　retardancy　of　BNNS　contributed　to　the　material＇s　persistent　fire-warning　performance.　©　2024　Elsevier　B.V.