Sulfonated aromatic polymers such as polyarylene ether nitriles (SPEN) have been extensively investigated to substitute commercial Nafion due to the high proton conductivity, excellent thermal and mechanical properties, and oxidation resistance. Besides, polar nitrile group in sulfonated aromatic polymers could decrease the swelling of membranes and enhance the adhesion between membranes and electrode layers. Meanwhile, graphene oxide (GO), an atomic-layer thick nanosheet containing oxygen-rich functional groups, has been researched extensively for applications in water permeability, supercapacitors, anti-fouling and anti-bacterial properties, attracting more and more researchers to pay attention to it. To our best knowledge, few researchers report the synergistic effects of SPEN and GO applied in the field of proton exchange membrane fuel cell. In this study, we have designed a series of GO/SPEN composite membranes by solution casting technique and investigated the thermal, mechanical properties, proton conductivity and methanol permeability. As a result, the composite membranes possessed better thermal and mechanical properties than pure SPEN. Besides, the composite membranes exhibited excellent proton conductivity, which is higher than that of pure SPEN and Nafion 117 membranes, while the methanol permeability is lower. All the data proved that the GO is an effective filler to improve performances of pure SPEN.