Nitric acid modified Mesoporous carbon (CMK-3) supported Pt particles have been prepared by chemical reduction with as a reducing agent. Energy dispersive spectrometer shows that the catalysts have some oxygenic functional groups. The activity of the composite catalysts for methanol electro-oxidation was investigated by using cyclic votammogram and chronoamperometry in acid media. The results indicated that modified mesoporous carbon can improve the catalytic ability of Pt catalyst for methanol electro-oxidation and antipoison capability for CO. The composite electrode modified by 0.23 g nitric acid has the highest electrochemical ability.