Density functional theory has been employed to investigate the interaction between NiMn bimetal and MgO support,further to investigate the influence of the interaction on H adsorption and H2 dissociation,and the results were compared with those on Ni/MgO.Two catalyst models,i.e.,perfect and defective MgO supported Ni2Mn2 clusters were built to represent the modeling catalyst.The results show that the interaction of defective MgO and active component Ni2Mn2 is stronger than that between perfect MgO and active component Ni2Mn2,and the adsorption of H on defective Ni2Mn2/MgO is stronger than that on perfective one,and further,H2 dissociation is favorable on defective Ni2Mn2/MgO compared that on perfect Ni2Mn2/MgO.Compared to MgO supported Ni4,the addition of a second metal Mn makes the interaction between active component and MgO support decrease,correspondingly,the ability of H adsorption is increased while the ability of H2 dissociation is reduced.This study provides the theoretical clue for experimental preparation to modify the interaction of metal and support through addition a second metal,further to tune the catalyst performance.