Using　the　amino　group　on　the　surface　of　g-C3N,　nanosheet,　chemically　cross　-linked　with　the　benzyl　group　chloride　of　the　chloromethylated　polyether　sulfone　(OWES),　which　is　the　membrane　substrate,　then　g-C3N4/CMPES　composite　membrane　was　provided　by　the　phase　inversion.　The　effects　of　the　addition　of　g-C3N,　nanosheets　on　the　structure,　morphology,　and　filtration,　photocatalysis,　antifouling　performance　of　composite　membranes　were　systematically　studied,　meanwhile　the　mechanism　of　photocatalytic　degradation　of　bovine　serum　albumin　(BSA)　solution　was　also　discussed.　The　results　showed　that　the　photocatalytic　performance　and　stability　of　the　composite　membrane　were　effectively　improved　by　chemical　bond　between　the　g-C3N,　nanosheets　and　the　membrane　substrate　material.　Due　to　the　photocatalytic　effect　and　the　hydrophilicity　of　g-C,N,　nanosheets,　the　composite　membrane　shows　excellent　filtration　performance　and　anti　-pollution　performance.