The geometries and optical adsorption properties of Au32-nPdn (n = 1, 2, 4, 6) alloy clusters were investigated within the static and time-dependent density functional theory. Our results confirm that Pd atoms favor to replace the inner Au atoms rather than the surface Au atoms of the cluster, which agrees well with previous reports. The optical adsorption property of the Au-32 cluster is significantly changed by the Pd doping. Our calculations show that the optical adsorption of Pd-doped alloy cluster in the visible light region is remarkably enhanced compared to the pure Au-32 cluster, especially in the lower energy sections. The analysis of the electronic structures of Au26Pd6, Au-32 and Pd-32 were performed to reveal the roles of doped Pd atoms. It is found that the doped Pd atoms increase the density of state around the Fermi level of the alloy clusters, which causes the enhanced optical adsorption of the Au Pd alloy cluster in the visible light region. (C) 2015 Elsevier B.V. All rights reserved.