Al-Ce and Al-Mg-Ce alloy fuels were prepared by melting method, which the mass fraction of Mg is 15% and the mass fraction of Ce are 0%, 1%, 3%, 5% . The phase composition, oxidation exothermic performance and appearance/element distribution of alloy fuels were characterized by XRD, TG-DTA and SEM/EDX. The reason of differences in oxidation exothermic reaction between alloys with different mass fraction of rare earth Ce and the oxidation behavior of Al-Mg-Ce alloys were analyzed. The results show that the oxidation exothermic performance of Al-Mg-Ce alloys reduces gradually with the increasing of Ce content. The first oxidation reaction temperature of Al-Mg-Ce alloy powders is about 160℃ lower than Al-Mg alloy powders due to the addition of Ce. Al-15Mg-1Ce alloy powders behave better thermal performance with the heat enthalpy of 6413uV?s/mg and weight increasing 90% at 1300℃ among them.