The electronic and physical properties of PtmPdn (m+n≤ 5) metal clusters and their interactions with dioxygen have been studied by using hybrid density functional B3LYP method.The total energies,atomization energies,vibration frequencies,and charge distributions were reported.The Pt-Pt bridge site modified by Pd atoms was found to be the most active site for the dissociation of dioxygen,which was mainly due to the change of electronic structures of the Pt atoms in bimetallic Pt-Pd clusters.