Generally, the process of separating the aliphatic hydrocarbon and aromatic hydrocarbon mixture from the hydrocarbon mixture has the relation with the various refining and petrochemistry processes. The traditional processes have the defect that there is lots of the energy consumption and the cost is high. In pervaporation process, the liquid mixtures were separated into permeate and retentate as result of direct contact with one side of a dense membrane and the permeated product is removed as a vapour from the other side by applying pressure. To resolve this problems, the development of the pervaporation membrane in which the process is simple and the separation performance is excellent are necessary. Benzene component can be preferentially removed from the gasoline feed due to higher affinity in the membrane. Recently, pervaporation applications in the removal of benzene from gasoline have attracted increasing attention worldwide. PEG-containing copolyimides were synthesized using one dianhydride and two diamines by chemical imidization and Sulfonated SEBS was successfully prepared using acetyl sulfate that reacted with sulfuric acid and acetyl anhydride. Prepared membranes tested for the separation of aliphatic/aromatic hydrocarbons by pervaporation. Chemical structure of copolyimides was evaluated using 1H NMR and FT-IR. The sorption properties of membranes were studied by swelling experiments. Pervaporation experiments for the investigation of the performance of the membrane were conducted at various temperature with benzene/1-hexene/n-heptane mixtures as feed streams. Experimental results showed that total flux increases with increasing of benzene concentration. Introduction of PEG units in the polymer generally showed very high hydrocarbon permeability than another polymer membrane without PEG segment, but this polymer also caused a decrease of selectivity.