The Ni-xPt-25Al (x = 0, 10, 20 and 30 at.%) alloys were fabricated by cold crucible levitation melting under argon atmosphere on a water-cooled Cu crucible. The effects of Pt contents on crystal structures, oxidation kinetics, morphologies of oxides, and oxidation resistance of the Ni-xPt-25Al alloys were studied using X-ray diffraction, simultaneous thermal analyzer, scanning electron microscopy, and X-ray photoelectron spectroscopy. The experimental results showed that Pt-modified Ni3Al-based alloys still kept γ′ phases with Pt contents increasing. The heating up and isothermal periods yield to the linear and parabolic kinetic laws, respectively. Pt plays a beneficial role in promoting the formation of oxides, meanwhile, the increased addition of Pt also improved the integrality and compactness of the oxide films.