Real-time　monitoring　of　environmental　relative　humidity　(RH)　plays　a　crucial　role　in　ensuring　both　the　quality　of　industrial　production　and　the　quality　of　life.　In　this　work,　polarization　maintaining　fiber　(PMF)　was　used　as　carriers　to　creatively　constructed　multi-layer　film　surface　functionalization　on　its　cladding　surface.　The　indium　tin　oxide　(ITO)　film　and　polyvinyl　alcohol　(PVA)　doped　graphite　oxide　(GO)　composite　polymer　constitute　multilayer　humidity　sensitive　film,　which　has　the　effect　of　dual　absorption　of　water　and　improves　the　humidity　sensitivity.　Microporous　composite　polymer　films　created　by　laser　processing　increase　the　area　for　water　evaporation　and　absorption,　which　improve　response　speed,　and　reduce　recovery　time.　The　surface　functionalized　PMF　sensor　exhibits　high　sensitivity　and　rapid　response　to　humidity,　achieving　bidirectional　repeated　measurement　of　0.28　nm/%　within　10　s　in　the　measurement　range　of　30%-90%,　rendering　it　a　reliable　means　for　realtime　monitoring　of　humidity.