The electronic structure and formation energies of Ni-doped CuAlO2 are calculated by first-principles calculations.Our results show that Ni is good for p-type doping in CuAlO2.When Ni is doped into CuAlO2,it prefers to substitute Al-site.NiAI is a shallow acceptor,while NiCu is a deep acceptor and its formation energy is high.Further electronic structure calculations show that strong hybridization happens between Ni-3d and O-2p states for Ni substituting Al-site,while localized Ni-3d states are found for Ni substituting Cu-site.