Abstract: Two possible mechanisms (the intermediate dissociation mechanism and the redox mechanism) of reverse water-gas reaction on Fe₃O₄(111) surface were investigated by means of the density functional theory(DFT).The most stable adsorption configurations of all species were verified by optimizing initial configurations. Through comparing the activation energies of dominant elementary reactions in two mechanisms, it was found that the redox mechanism is dominant, while the intermediate dissociation mechanism is difficult to occur. Furthermore, the octahedral Fe atom was found to play an important role during adsorption and activation.