The　manipulation　of　surface　wettability　has　been　regarded　as　an　efficient　strategy　to　improve　the　membrane　performances.　Herein,　the　counterionswitched　reversibly　hydrophilic　and　hydrophobic　surface　of　TiO2-loaded　polyelectrolyte　membrane　are　prepared　by　layer-by-layer　assembly　of　poly(sodium　4-styrene　sulfonate)　(　PSS)　and　poly(diallydimethyl-ammoniumchloride　(PDDA)　containing　TiO2@PDDA　nanoparticles　(NPs)　on　the　hydrolyzed　polyacrylonitrile　(PAN)　substrate　membrane.　The　obtained　polyelectrolyte　multilayer　(PEM)　membranes　[PEM-TiO2](4.5)X-+(-)　(X-　=　Cl-,　PFO-　[perfluorooctanoate]　etc.)　show　different　hydrophilicity　and　hydrophobicity　with　various　counterions.　The　integration　of　TiO2　NPs　obviously　improves　the　wettability　and　nanofiltration　(NF)　performance　of　PEM　membrane　for　(non)aqueous　system　of　dyes　(crystal　violet,　eriochrome　black　T)　with　a　high　recyclability.　The　highly　hydrophilic　[PEM-TiO2]　4.5(+)Cl(-)　(water　contact　angle　[WCA]:　13.2　+/-　1.8　degrees)　and　hydrophobic　[PEM-TiO2]　4.5(+)PFO(-)　(WCA:　115.4　+/-　2.3　degrees)　can　be　reversibly　switched　via　counterion　exchange　between　Cl-　and　PFO-,　verifying　the　surface　with　a　reversible　hydrophilic-hydrophobic　transformation.　For　such　membranes,　the　morphology,　wettability,　and　NF　performance　rely　on　the　loading　of　TiO2@PDDA　NPs　and　surface　counterion.　Meanwhile,　the　motion　and　interaction　of　water　or　ethanol　in　the　hydrophilic　or　hydrophobic　membrane　are　revealed　by　low-field　nuclear　magnetic　resonance.　This　work　provides　a　facile　and　rapid　approach　to　fabricate　smart　and　tunable　wetting　surface　for　potential　utilization　in　(non)aqueous　NF　separation.