The preparation of the composite membranes has been investigated by photo-induced graft filling polymerization. The asymmetric polyimide membranes as substrate were prepared by the phase inversion process using polyimide with ben zophenone structure. Graft polymerization took place by UV irradiation supplying monomer, such as methyl acrylate without adding photoinitiator like benzophenone. These graft modified membranes showed benzene permselectivity for benzene/cyclohexane mixture (50/50 v/v) on pervaporation.