It is investigated for the interactions of bimetal NiCo with MgO as well as its effects on the H adsorption and H-2 dissociation using a density functional theory method. Two models, Ni2Co2 cluster supported on perfect MgO(001) and oxygen-vacancy MgO(001) are used to represent bimetal NiCo deposited on MgO catalysts. The results show that the Ni2Co2/MgO catalyst with oxygen-vacancy exhibits stronger metal-support interaction compared to the perfect Ni2Co2/MgO, however, it has the weaker H adsorption ability as well as the better H-2 dissociation activity. Compared with Ni-4/MgO, the interaction between metal and support is weaker on the corresponding Ni2Co2/MgO, and H adsorption is stronger as well as the H-2 dissociation is accelerated. The results indicate that both addition of a second metal Co and modification the support MgO can tune the metal-support interaction, further to change the H adsorption ability, meanwhile improve the activity of H-2 dissociation. This work finely identifies the experimental result that tune the metal-support interaction can improve the catalyst's performance. (C) 2016 Elsevier B.V. All rights reserved.