Nanocrystalline Pt-Ce oxides were prepared by citric acid method and impregnation method, and then mounted on cordierites to investigate the catalytic behavior for methane oxidation under scarce oxygen environment. XRD, H-2-TPR, TEM, and XPS were employed to investigate the relationship between physicochemical characteristics and catalytic performances. Pt-CeO2 showed good activity for oxygen conversion in fuel rich condition, especially during extinction step, with a huge hysteresis loop. By varying the oxygen concentration, Pt-CeO2 catalysts were poisoned by oxygen along ignition, and the competitive adsorption of oxygen and methane inhibits the activation of methane. Owing to the interaction between Pt and CeO2, and a more homogeneous dispersion of Pt in CeO2 compared with that of Pt/CeO2 prepared by impregnation, Pt-CeO2 catalysts maintained high activity during calcination and pretreatments.