CO2 methanation is an important measure to address current environmental issues. Ni-Fe bimetallic catalysts have been widely used in CO2 methanation reactions, but there is limited research on their synergistic effects and reaction mechanisms. In this paper, Ni/Al2O3 and Ni-Fe/Al2O3 catalysts were prepared by hydrothermal method and evaluated experimentally, and the effect of Fe doping on CO2 methanation was investigated through a combination of experiment and theory. The experimental results show that Ni-Fe catalyst has better catalytic performance, with a CO2 conversion rate of 84.24% and a CH4 selectivity of 83.53% at a temperature of 375 ℃. DFT calculations show that the introduction of the second metal element Fe dilutes the surface of Ni-Fe and alters its electronic properties. The Ni-Fe surface not only enhances the adsorption of CO2 on the catalyst surface, resulting in a higher degree of CO2 activation, but also makes the dissociation of H2 easier, which is conducive to the progress of hydrogenation reactions. In addition, the introduction of Fe also changes the reaction pathway of CO2, directing the reaction towards the generation of CH4, The specific pathway is CO2*→HCOO*→HCOOH*→H2COOH*→H2CO*→H3CO*→CH4*.