Abstract: The geometrical structure of Ni doped 32-atom supercell of AlN was investigated using the ultra-soft pseudopotential method of total-energy plane wave based on the density functional theory (DFT). Band structures, partial density of states, mulliken charges, electron density differences and total-energy of Ni doped AlN crystals were calculated and analyzed in details. The results revealed that The Ni dopants were found spin polarized. Band structures show a half metallic behaviour. The ferromagnetic ground state in Ni-doped AlN can be explained in terms of p-d hybridization mechanism. These results suggest that Ni-doped AlN present a promising dilute magnetic semi-conductor.