Abstract: The NiO/MgO catalysts were prepared by impregnation and calcination at different temperatures, and then were characterized by TPR, XRD, BET and Chemisorption techniques. The performance of NiO/MgO catalysts in coupling the partial oxidation of methane and CO2 reforming to prepare syngas was studied in a fixed-bed reactor. The results show that a solid-solution complex of NixMg1－xO is formed when NiO/MgO catalyst is calcined at 800 ℃. Although the complex catalyst exhibits low reducibility compared with the catalysts calcinated at low temperatures, a higher metal dispersion and a smaller Ni cluster size can be acquired. Because metallic Ni still remains strong interaction with MgO, the sintering of Ni is prevented. Thus, the carbon deposition is inhibited, which contributes to the high stability of the NixMg1－xO catalyst. While for the catalyst calcined at 900 ℃, low initial activity is exhibited due to the formation of much uniform bulk solid solution that is more difficult to be reduced to metallic Ni.