The combustion of fossil fuels can produce sulfur dioxide (SO2), which is a major source of the environmental problems such as acid rain, photochemical smog and ozone depletion. To solve these problems, it is urgent to develop new porous materials that are conducive to remove acid gases such as SO2. In this work, the adsorption and separation properties of SO2 from flue gases (SO2CO2N2) by covalent organic frameworks (COF) were systematically studied based on the grand canonical Monte Carlo simulations. The results of the structure-activity relationships show that the separation performance of SO2 is related to the pore volume (Vpore) and accessible surface area (ASA) of COF materials to some extent. Some promising candidates with high SO2 adsorption capacity and separation selectivity were identified by comprehensive evaluation metrics, and it can found that the existence of appropriate functional group and the small channels are more conducive to gas adsorption. In addition, the energy decomposition and IGM analysis indicate the nature of the adsorption of SO2 on CF3-TFP-TTA is mainly originated from the electrostatic attraction. These results can provide theoretical references for the design and synthesis of novel high-performance adsorptive separation material.