A　commercial　polyacrylonitrile　(PAN)　was　pretreated　and　modified　to　obtain　the　substrate　HPAN,　and　a　ground　MOF　material　PCN-250　as　filler　was　blended　with　polyethyleneimide　(PEI)　and　spin-coated　on　the　HPAN　substrate　to　obtain　a　PCN-250　/　PEI-HPAN　mixed　matrix　membrane　for　nanofiltration.　The　characterization　of　MOF　and　the　prepared　mixed　matrix　membrane　showed　that　the　ground　PCN-250　had　good　dispersion　in　water,　and　with　the　increase　of　the　amount　of　PCN-250　used　in　the　membrane　preparation　process,　the　roughness　of　the　membrane　surface　and　the　effective　area　increased　accordingly.　Since　the　grain　surface　of　PCN-250　was　negatively　charged,　the　addition　of　PCN-250　into　polymer　matrix　resulted　in　high　negative　charge　on　the　membrane　surface,　which　improved　its　performance　in　the　rejection　of　anionic　dyes.　We　also　characterized　the　membrane　by　SEM　and　AFM　and　optimized　the　membrane　preparation　procedure.　Results　show　that　when　the　loading　of　PCN-250　was　75%,　the　nanofiltration　performance　of　the　PCN-250　/　PEI-HPAN　membrane　pair　was　the　highest,　with　water　permeability　of　1　480　L　/　(m2.h.MPa),　and　a　rejection　of　97.　3%　to　the　dye　methyl　blue.　©　2023　Beijing　University　of　Technology.　All　rights　reserved.