According to the method, it is assumed that cracks in a coal seam are three groups of joints which are mutually orthogonal; By considering the anisotropy of fracture structure, joint mechanics parameters, coal matrix adsorption/desorption deformation and ground stress, evolution model of absolute permeability of orthotropic coal seam fissures under effective stress change and gas adsorption/desorption under the dual action is set up. The invention is closer to the real coal seam fissure structure than the previous coal seam absolute permeability model, so it can more accurately predict the evolution law of the absolute permeability in the coalbed methane mining and coal seam gas drainage process.