The reforming mechanism of CO2-CH4 on Nano scale Ni metal catalyst was investigated using the B3LYP density functional method and MP2/Lanl2dz method. It was found that the reaction include thirteen steps and the activation energy of each step was 44.7175, 200.4707, 171.0781, 307.2596, 124.5252, 330.7904, 593.9056, 177.5526, 226.6793, 277.789 2, 394.5525,399.5340 and 105.4115 kJ·mol-1. The rate determining step was the fourth step. The enthalpy value of each step was 31.6136, 106.7138, -104.2589, 79.9641, 93.5573,174.6 121, 259.6409, -141.9192,...