Abstract: Enhanced coalbed methane (ECBM) technology shows significant potential in improving methane recovery and enabling CO₂ geological sequestration in deep coal seams. However, field practices indicate that merely increasing injection pressure fails to achieve ideal CH₄ production enhancement, as the underlying microscopic displacement mechanisms remain unclear. To address this, a molecular model of an anthracite unit cell was constructed. Combining Grand Canonical Monte Carlo (GCMC), Molecular Dynamics (MD), and Density Functional Theory (DFT) simulations, the adsorption isotherms and the interaction energies of CO₂, CH₄, and N₂ on coal were quantitatively analyzed, and the displacement processes of adsorbed CH₄ by CO₂/N₂ were simulated under both isobaric and high pressure injection conditions. The variations in gas diffusion coefficients and displacement rates were investigated from a molecular perspective. The results reveal that the adsorption capacities of the three gases on the anthracite model follow the order (CO₂ > CH₄ > N₂),and the interaction energies mainly arise from the dispersion component of van der Waals forces. The displacement process comprises two main stages: initially, high pressure injection is dominated by pressure-driven flow, rapidly producing free-state CH₄ with a displacement rate 2.4 to 3.6 times higher than that under isobaric diffusion, although this rate decays rapidly with increasing pressure. As the system approaches diffusion equilibrium, the pressure-driven flow gradually ceases to dominate, and the displacement mechanism becomes dominated by competitive adsorption, where adsorbed CH₄ is desorbed and contributes significantly to the total production. The overall CH₄ displacement volume is co-controlled by the competitive adsorption effect and the reduction in CH₄ partial pressure. During isobaric injection, CO₂ yields the optimal CH₄ displacement outcome due to its stronger competitive adsorption capacity and a more pronounced decrease in CH₄ partial pressure. Furthermore, higher injection pressures lead to lower sustained CH₄ displacement efficiency after system equilibrium, with displacement rates decreasing by approximately 34% to 54%, indicating that excessively high injection pressure is detrimental to maintaining long-term stable CH₄ production.