The addition of Pt on NiO-MgO solid solution enhanced the performance of oxidative steam reforming of methane, especially, the catalyst can be activated during the oxidative reforming of methane at low reaction temperature like 823 K. 0.1% Pt/Ni0.2Mg0.8O exhibited much higher performance than 0.1% Pt/MgO and Ni0.2Mg0.8O. From the comparisons, the additive effect of Pt to Ni0.2Mg0.8O is to promote both the activity of combustion and reforming of methane. This additive effect can be explained by the high combustion activity caused by the synergy of Pt with NiO-MgO solid solution and the high catalyst reducibility.