In　this　study,　a　novel　free　radical　graft　copolymerization　strategy　was　applied　to　prepare　the　catechin-modified　chitosan　loose　nanofiltration　(NF)　membrane　for　dye　desalination.　First,　catechin,　the　eco-friendly　natural　material,　was　grafted　onto　chitosan　through　a　free　radical　reaction　and　self-cross-linking.　Second,　the　catechin-grafted-chitosan　conjugates　were　assembled　onto　the　surface　of　the　hydrolyzed　polyacrylonitrile　(HPAN)　ultrafiltration　(UF)　membrane.　Finally,　the　prepared　membrane　was　characterized　by　FT-IR,　XPS,　SEM,　AFM,　electrokinetic　analyzer,　and　contact　angle　goniometer.　The　results　showed　that　the　prepared　membrane　exhibited　a　high　rejection　for　dyes　(i.e.,　99.6%　for　congo　red,　98.7%　for　acid　fuchsin,　and　98.5%　for　crystal　violet)　and　a　low　retention　for　inorganic　salts　(i.e.,　4.8%　for　Na2SO4,　12.5%　Na2SO4　rejection,　especially,　was　2-3　times　lower　than　that　of　the　reported　loose　NF　membranes.　Meanwhile,　a　high　removal　rate　of　82%　for　NaCl　with　a　dye　loss　rate　of　10%　was　also　observed　in　the　constant-volume　batch　dye　desalination　process.　Moreover,　the　membrane　also　possessed　a　good　dye　antifouling　ability　with　a　flux　recovery　ratio　of　87.8%　and　an　irreversible　fouling　ratio　of　12.2%.　Hence,　this　catechin-modified　chitosan　loose　NF　membrane　shows　a　promising　application　for　dye　desalination.