CO2-CH4 reforming into syngas is an effective approach to the utilization of these two greenhouse gases. In this study, nano-structured Ni-based catalysts supported on spinel (MgAl2O4) for CO2-CH4 reforming were synthesized and evaluated under 750-900 degrees C, it performed with extremely high catalytic reactivity that the conversions of CO2 and CH4 were 90% and 97% at 900 degrees C, with gas hourly space velocity (GHSV) as high as 912,000 ml g(Cat)(-1) h(-1), which is 76 times higher than the GHSV reported in other literatures. Also, the nanostructured Ni based catalysts showed excellent durability with nearly zero deactivation in 10 h. Interestingly, the Ni-based catalysts did not need initial H-2 reduction as required with state-of-the-art reforming catalyst. The fresh Ni-based catalysts mainly consist of NiO and MgAl2O4 crystallites, while the spent ones mostly contain Ni-0 (about 10 nm) and MgAl2O4 crystallite.