Blending　hydrophilic　additives　is　an　effective　method　to　improve　the　surface　hydrophilcility　and　antifouling　property　of　ultrafiltration　membranes.　In　this　study,　we　prepared　a　series　of　polysulfate　(PSE)　hollow　fiber　membranes　(HFMs)　containing　a　zwitterion-based　copolymer,　poly(4-vinylpyridine-co-methylacryloxyethyl　phosphocholine),　with　varying　monomer　ratios　and　blending　quantities.　The　relationship　between　cast　solution　properties　and　phase　separation　behavior　was　investigated,　as　well　as　the　impacts　of　copolymer　composition　and　amount　on　the　separation　performances　and　antifouling　abilities　of　the　membranes.　A　higher　hydrophilic　monomer　ratio　and　more　copolymer　addition　of　zwitterionic　copolymer　would　facilitate　surface　segregation,　increasing　the　hydrophilicity　of　membrane　surface　and　generating　a　dense　hydration　layer.　This　layer　can　resist　macromolecule　contaminants　and　promote　water　molecular　transport.　Furthermore,　a　more　compacted　skin　layer　improves　separation　ability.　The　optimized　PSE　HFMs　had　water　fluxes　around　140　L　m−2　h−1,　BSA　rejections　over　97　%,　and　flux　recovery　rates　over　92　%　during　operation.　Moreover,　the　membrane　demonstrated　ultra-low　flux-sacrifice　when　applied　to　protein　solutions　while　maintaining　a　high　rejection　rate,　which　indicates　the　distinctive　and　strong　competitiveness　of　PSE/P(4VP-co-MPC)　HFMs.　©　2024