NiAl coating obtained by pack aluminization is the firstly used as Al₂O₃-forming high-temperature coating. Since the middle of the last century, NiAl coatings were employed in hot sections of aero-engines for protection against high temperature oxidation. Investigations of the oxidation mechanisms of the coating, and exploration of the coating techniques continue up to now. On a basis of understanding to the oxidation mechanism of alloys and thermal growth of Al2O3, a concept of improving the oxidation resistance of nickel aluminide coating by means of grain refinement and typical metal oxide dispersions has been proposed. Meanwhile a method to refine the grains of the nickel aluminide coating and disperse it with metal oxide nanoparticles has been presented, and key factors (including growth rate of the Al₂O₃ scale, Al₂O₃ phase transformation from metastable phases to the stable phase, the Al₂O₃ adhesion to the coating as well as the interdiffusion between the coating and the metal substrate) intrinsically correlated with the oxidation resistance of the coating which can be significantly affected by its modification in microstructure and chemical composition have been reviewed. The new result is expected to be helpful to further offer theoretical and experimental bases for tapping the potential and prolonging the service life of the aluminized coatings in application.