Introducing　hydroxyl　(OH)　groups　onto　the　surface　of　chemically　inert　hexagonal　boron　nitride　(h-BN)　is　conducive　to　the　exfoliation　and　functionalization　of　h-BN,　meanwhile　could　enhance　the　intermolecular　forces　with　polymer　as　well.　However,　chemical　inertness　generated　by　partially　ionized　B-N　bonds　makes　the　introduction　of　OH　groups　still　remains　a　challenge.　Here,　we　reported　a　scalable　one-step　thermal　calcination　method　for　the　fabrication　of　OH-functionalized　h-BN　nanosheets　(OH-BN).　Then,　transparent,　strong,　and　flexible　as　well　as　flame　retardant　nanocomposite　films　of　as-prepared　OH-BN　and　PVA　were　prepared　through　an　aqueous　solution　casting　technique.　Due　to　hydrogen-bond　self-assembly　and　crystalline-region　self-relief,　elongation　at　break,　tensile　strength,　and　Young＇s　modulus　of　PVA　nanocomposite　film　were　simultaneously　increased　by　109.3%,　73.6%,　and　144.4%　with　as　low　as　0.2　wt　%　OH-BN.　Besides,　the　self-stiffness　phenomenon　that　damages　the　material　elasticity　during　dynamic　service　process　of　PVA　nanocomposite　films　was　effectively　hindered.　Meanwhile,　the　superior　visible　light　transmittance　and　higher　absorption　quality　to　UV-light　were　also　confirmed,　which　promoted　its　practical　use　in　artificial　cornea　materials.　Attributing　to　the　well-dispersed　state　and　layered　structure,　incorporated　OH-BN　presented　a　barrier　function　to　suppress　the　delivery　of　thermal　degradation　products　of　PVA　matrix,　thus　enhancing　thermal　stability　and　fire　safety.　Herein,　we　come　to　a　conclusion　that　the　scalable　one-step　synthesis　of　OH-BN　and　environmentally　friendly　fabrication　of　PVA/OH-BN　nanocomposite　films　as　well　as　excellent　properties　greatly　contribute　to　the　development　of　the　practical　application　of　h-BN　nanosheets,　thus　obtaining　multifunctional　composite　materials.