The density functional theory (DFT) and self-consistent periodic calculation were used to investigate the methanol adsorption on the Pt-Mo(111)/C surface. The adsorption energies,equilibrium geometries and vibration frequencies of CH3OH on nine types of sites on the Pt-Mo(111)/C surface were predicted and the favorite adsorption site for methanol is the top-Pt site.Both sites of valence and conduction bands of doped system have been broadened, which are favorable for electrons to transfer to the cavity. The possible decomposition pathway was investigated with transition state searching and the calculation results indicate that the O-H bond is first broken, and then the methanol decomposes into methoxy. The activation barrier of O-H bond breaking with Pt-Mo catalyst is only 104.8 kJ mol-1, showing that carbon supported Pt-Mo alloys have promoted the decomposition of methanol. Comparing with the adsorption energies of CH3OH on the Pt(111)/C surface and that of CO, the adsorption energies of CO are higher, and Pt(111)/C is liable to be oxidized and loses the activity, which suggests that the catalyst Pt-Mo(111)/C is in favor of decomposing methanol and has better anti-poisoning ability than Pt(111)/C.