The　compatibility　and　dispensability　of　inorganic　nanofillers　within　a　polymer　matrix　is　crucial　for　the　separation　performance　of　mixed　matrix　membranes.　Using　organic　compounds　to　modify　the　surface　of　inorganic　nanoparticles　is　commonly　used　to　reduce　the　agglomeration　of　nanoparticles　and　to　therefore　improve　the　compatibility　between　the　nanoparticles　and　the　polymer　matrix.　In　this　study,　graphene　oxide　(GO)　nanosheets　were　modified　by　in-situ　polymerized　hyperbranched　poly　(methylene　bisacryl　amide　amino　ethyl　piperazine)　(HPMA)　through　electrostatic　interactions.　The　modification　of　GO　and　polymerization　of　HPMA　were　simultaneously　achieved.　The　HPMA-modified　GO　nanosheets　were　then　used　to　fabricate　separation　membranes　on　ceramic　tubular　substrates　via　a　vacuum-assisted　assembly　method.　The　chemical　structure　of　HPMA　molecules　and　the　HPMA-modified　GO　nanosheets　were　confirmed　by　FT-IR,　Raman,　and　H-1　NMR　spectroscopy.　Raman　mapping　verified　that　the　GO　nanosheets　were　dispersed　well　in　the　polymer　matrix.　The　HPMA-GO　composite　membranes　thus　prepared　were　used　to　separate　methyl　tert-butyl　ether　(MTBE)/methanol　(MeOH)　mixture　by　pervaporation.　The　optimized　MeOH　content　in　permeation　and　flux　could　reach　99.5　wt%　and　0.41　kgm(-2)　h(-1),　respectively,　when　the　feed　MeOH　content　was　10　wt%　at　40　degrees　C.　The　composite　membranes　also　showed　a　good　stability　in　a　120-h　running　test.　Therefore,　the　facile　method　presented　in　this　study　could　provide　a　new　avenue　to　fabricate　mixed　matrix　membranes　for　pervaporation　separation　of　MTBE/MeOH　mixtures　and　other　applications.