Halide　perovskite　presents　great　competitive　advantages　in　the　new　generation　of　stimuli-responsive　materials,　while　the　tuning　of　fluorescence　emission　is　still　limited　by　irritative　factors　and　external　conditions.　Herein,　anti-solvent　assisted　crystallization　and　in-situ　synthesis　are　innovatively　combined　to　accomplish　the　fiberized　self-assembly　of　copper-based　perovskite　quantum　dots　economically　and　environmentally,　which　makes　humidity　a　novel　stimulus　for　luminescence　regulation.　Under　the　excitation　of　medium-wave　UV,　the　original　Cs3Cu2I5-CsCu2I3@polyacrylonitrile　(CCI@PAN)　fibers　exhibit　a　main　emission　peak　of　460　nm　with　a　shoulder　at　550　nm,　and　the　intensity　of　shoulder　peak　is　gradually　increased　with　the　continuous　addition　of　moisture.　Switching　from　blue　to　yellow　fluorescence　is　achieved　in　CCI@PAN　fiber　membrane　by　the　introduction　of　water,　which　is　attributed　to　the　ultra-high　solubility　of　CsI　in　water.　Moreover,　owing　to　the　spatial　limitation　of　the　nanofibers,　the　unique　incomplete　reversibility　exhibited　by　the　nanofiber　membrane　during　water　removal　predicts　that　the　nanofiber　membrane　can　be　used　as　a　permanent　recording　material.　Overall,　this　work　deeply　explores　the　influence　of　humidity　on　the　fluorescence　and　structure　of　perovskite　quantum　dots,　providing　a　method　to　synthesize　innovative　perovskite　nanofiber　composites　based　on　emission　conversion,　which　has　broad　prospects　in　advanced　anti-counterfeiting,　biological　protection　display,　information　encryption　and　smart　wearable　devices.　©　2024　Elsevier　B.V.