This study simulated the adsorption and separation of CO₂ by the metal-organic frameworks material M-MOF-74, established the skeleton model of M-MOF-74 series adsorbent, and calculated the adsorption of CO₂ pure component gas and CO₂/N₂ mixed gas on M-MOF-74 series adsorbent by the grand canonical Monte Carlo method. Among the CO₂ adsorption performances of MOF-74 materials with metal centers of Mg, Co, Ni, and Zn, Mg-MOF-74 had the highest CO₂ adsorption capacity, adsorption selection coefficient and adsorption heat. When mixed gas was adsorbed, the law of CO₂ adsorption was consistent with that of pure CO₂ adsorption. The size law of adsorption heat on MOF-74 was similar to that of adsorption amount. Our findings demonstrated that the interaction between the metal-organic framework material and CO₂ is greater than that between the material and N₂. The interaction between the gas and the MOF-74 series adsorbent was the main factor affecting the adsorption amount, which reveals the strong influence of metal central atoms on the amount of gas adsorption. Our findings provide new ideas for the design of efficient adsorbent materials.