Nafion modified Pt nano-particles with size about 4 nm were synthesized.The modified particles were absorbed on the surface of carbon nanotubes and used as electro-catalysts for proton exchange membrane fuel cell. Due to the plentiful proton channels provided by the modifying Nafion ionomers, the single fuel cell with the modified Pt catalyst has a promised performance. The output was 0.282 W/cm2 with Pt loading of 0.1 mg/cm2, better than that of unmodified one, which was 0.273 W/cm2 with Pt loading of 0.11mg/cm2.