Anti-fouling　property　is　of　vital　significance　and　remains　a　challenge　in　the　membrane　separation　field.　In　this　work,　N-diethylethylenediamine　(DEEDA)　was　incorporated　into　the　polyamide　matrix　first.　Then,　an　anti-fouling　zwitterionic　nanofiltration　membrane　with　tunable　surface　charge　was　fabricated　by　the　grafting　of　p-xylylene　dichloride　(XDC)　on　the　membrane　surface.　The　resulting　nanofiltration　membrane　possessed　zwitterionic　groups　of　positively　charged　N+　and　negatively　charged　COO-.　Meanwhile,　the　surface　charge　could　be　tuned　precisely　by　the　concentration　of　XDC.　A　neutrally　charged　nanofiltration　membrane　was　obtained　when　the　concentration　of　XDC　was　1.0　​wt%　and　the　preparing　membrane　showed　permeance　of　9.1　​L·m-2·h-1·bar-1　with　high　rejection　of　CaCl2　(90.8%)　and　Na2SO4　(91.3%)　at　pH　​=　​6.5.　This　membrane　exhibited　excellent　anti-fouling　properties　towards　not　only　negatively　charged　bovine　serum　albumin　but　also　positively　charged　lysozyme.　The　optimum　membrane,　PA-XDC-1.0,　had　flux　recovery　rates　of　95.0%　and　94.0%　for　bovine　serum　albumin　and　lysozyme,　respectively,　which　was　higher　than　those　of　PA-DEEDA-0　(86.1%　and　80.7%).　This　work　offered　a　facile　way　to　fabricate　an　anti-fouling　zwitterionic　nanofiltration　membrane　with　tunable　surface　charge,　which　had　wide　applications　in　water　purification.　©　2022　The　Authors