Proton exchange membrane fuel cells(PEMFCs) are a promising alternative power sources to the traditional internal combustion engine for automobile applications due to their high power density, low greenhouse gas emissions, quick start up time. The proton exchange membrane(PEM) is an important component where the efficiency determining proton transfer occurs. Critical characteristics of a good PEM include fast proton conduction, good water transport, thermomechanical stability, and sustained durability under various operating conditions. Nafion membrane is composed of a hydrophobic polytetrafluoroethylene back bone and hydrophilic perflouorinated pendant side chains ending with sulfonic acid moieties. Although it comprises all of the aforementioned properties, high cost still persist in the system as the series limitations. This study relates to a polymer electrolyte membrane for improved performance PEMFC, were researched with respect to properties required for driving a fuel cell. First, to sulfonated a monomer for the preparation of new aromatic hydrocarbon-based polymer electrolyte membrane having ion conductivity. The bis(4-fluorophenyl)phenyl phosphine oxide was sulfonated using fuming sulfuric acid. Synthetic hydrophilic oligomer and the hydrophobic oligomer and the block copolymers were prepared via aromatic nucleophilic substitution polycondensation by adjusting the molar ratio(30%, 50%, 70%) of the hydrophilic oligomer. A block copolymer structure and degree of sulfonation was analyzed by 1H-NMR, FT-IR and gel permeation chromatography(GPC) analysis. Thermal stability was confirmed by thermo gravimetric analysis(TGA) and differential scanning calometry(DSC). In addition, the ion conductivity was measured in order to demonstrate the performance of PEMFC. Block copolymer was stable at high temperature(>200℃), the increase of sulfonic groups was improved conductivity. Excellent oxidation durability of the block copolymer is confirmed by the fenton test. The phase separation of the polymer was observed to make AFM analysis.