The　development　of　high-performance　nanofiltration　membranes　for　dye/salt　separation　remains　challenging　due　to　the　ubiquitous　permeability–selectivity　trade-off.　Conventional　MXene　membranes　suffer　from　structural　compactness　caused　by　irreversible　nanosheet　restacking,　which　severely　limits　their　water　permeability　and　separation　efficiency.　Herein,　we　propose　a　structural　engineering　strategy　using　ultralong　hydroxyapatite　(HAP)　nanowires　as　nanoscale　spacers　to　transform　conventional　2D　MXene　laminates　into　3D　mountain-like　architectures.　The　ultralong　HAP　nanowires　(length:　tens　of　micrometers;　diameter:　1000)　serve　as　effective　structure　mediators,　creating　abundant　water　transport　channels　while　preventing　MXene　nanosheet　restacking.　Comprehensive　characterization　reveals　that　the　optimized　HAP/MXene　membrane　exhibits　significantly　expanded　structural　parameters,　including　a　98.31　%　increase　in　surface　roughness,　12.05　%　rise　in　porosity,　and　26.05　%　enhancement　in　specific　surface　area　compared　to　pristine　MXene　membranes.　These　structural　advantages　translate　into　exceptional　separation　performance:　the　membrane　achieves　an　unprecedented　water　flux　of　608.50　LMH/bar　(1023.73　%　improvement)　while　maintaining　high　dye　rejection　rates　(＞98　%　for　Congo　Red)　and　minimal　salt　rejection　(　©　2025　Elsevier　B.V.