Fluorine-modified Ni-Mg-Al mixed oxides prepared by thermal decomposition of hydrtalcite-type (HT) precursor was characterized by XRD, EXAFS, TGA, SEM, TPD-CO2, TPR-H-2, N-2 adsorption/desorption technique, and then tested in the partial oxidation of methane (POM). The result revealed that fluorine was successfully introduced into Ni-Mg-Al mixed oxide via the high dispersion of MgF2, which led to the formation of the periclase-type catalyst with mesoporous structure. By compared with pure Ni-Mg-Al mixed oxides, they had the low surface area and crystallization with small particle size, but the high moderate and strong basicity. Such catalyst showed a high performance over POM without deactivation even after 120 h run at 1053 K. This could be attributed to the promotion effect of the F- anions, which improved the homogeneous distribution of nickel and basicity of the catalyst with high resistance to coking and sintering.