Abstract: The prospect of geological sequestration and storage of CO2 as a means of reducing global emission of this greenhouse gas and enhancing coalbed methane recovery (ECBM) has recently attracted worldwide interest due to the global warming and the resource shortage. Complicated coupled binary gas-solid interaction arises during carbon dioxide sequestration in a coal seam,which combines effects of CO2-CH4 counter adsorption, CO2-CH4 counter diffusion, binary gas flow and coal bed deformation.Through solving a set of coupled field governing equations, a novel full coupled Finite Element (FE) model was established by COMSOL Multiphysics. The new FE model was applied to the quantification of coal porous pressure, coal permeability, gas composition fraction and coal displacement when CO2 was injected in a CH4 saturated coal bed. Numerical results demonstrate that CH4 is swept by the injected CO2 accompanied by coal volumetric deformation. Compared to the single CH4 in situ, CH4-CO2 counter-diffusion induced coal swelling can make more compensation for coal shrinkage due to effective stress. Competing influences between the effective stress and the CH4-CO2 counter-diffusion induced volume change governs the evolution of porous pressure and permeability, which is controlled by the porous pressure correspondingly. Initially, the coal permeability keeps descending due to the coal swelling. Afterwards, it behaves rising when the porous pressure dominates the coal deformation. In this simulation, coal permeability rebounded at the 4.66×107s. This achievement extends our ability to understand the coupledmulti-physics of the CO2 geological sequestration and CO2 enhanced coal bed methane recovery under field conditions.