Polymeric　materials　with　charged　groups　present　satisfactory　performance　in　membrane　separation　due　to　their　strong　interaction　with　water　molecules.　However,　the　interactions　between　water　and　charged　groups　are　complex,　and　it　is　still　a　big　challenge　to　depict　the　role　of　charged　groups　on　the　pervaporation　performance　of　polymeric　membranes.　Here,　we　constructed　the　polyelectrolyte　complex　nanoparticles　(PECNPs)　with　four　different　charged　groups　and　adopted　them　for　preparation　of　pervaporation　membranes.　The　PEC　membranes　were　used　for　pervaporation　tests.　Low-field　nuclear　magnetic　resonance　(LF-NMR)　was,　for　the　first　time,　employed　for　identifying　how　the　water　survive　in　polymeric　membranes　with　different　charged　groups.　The　result　hints　that　the　water　state　in　the　membrane　varies　quite　different　for　the　four　kinds　of　PECNPs　membranes　(PECNPMs),　which　finally　determines　the　performance　of　the　prepared　PECNPMs.　The　PEC-SO(3)(-)membrane,　possessing　both　high　freezable　bound　water　and　non-freezable　bound　water,　showed　the　highest　separation　in　dehydrating　of　10　wt%　water/ethanol　mixtures　at　70　degrees　C,　with　a　pervaporation　separation　index　of　6.93　x　10(6),　which　outperforms　other　polymeric　membranes　reported.　Thus,　the　performance　of　PEC　membrane　can　be　well-tailored　by　the　conveniently　tailoring　charged　groups,　which　paves　a　solid　path　for　developing　high-performance　polymer　membranes.