The electrochemical nitrogen reduction reaction (ENRR) is one of the sustainable development technologies for the synthesis of NH₃ to replace the Haber-Bosch process. The core issue is to find stable electrocatalysts with high catalytic activity and selectivity. Since the transition metal oxynitrides (TMNO) surface follows the Mars-van Krevelen (MvK) mechanism pathway for ammonia synthesis reaction, it exhibits more favorable N₂ adsorption and activation than the conventional association mechanism. Based on this, Ni was selected to be loaded on dual-sites MoTiNO with the best ENRR performance, and the Ni-MoTiNO structure was constructed as an electrochemical N₂ reduction catalyst by the density function theory (DFT) calculation method, and four aspects, including the structural stability, two-site adsorption behaviors, ENRR catalytic activity based on the ^*H-migration-assisted MvK mechanism, and the analysis of the electronic properties, were investigated. Results show that the synergistic action of the dual sites (Ni and Nv) on the surface of Ni-MoTiNO both promotes ^*H migration and effectively breaks the linear proportionality between the strong adsorption of ^*N-related intermediates and the difficulty in resolving the products in ENRR. Experiments have proved that the synthesized Ni-MoTiNO can effectively achieve ammonia synthesis and has a relatively high selectivity.