<p>Coal mine underground reservoirs contain a large number of porous media material combination structure. In order to ensure the stability of reservoir water storage, it is meaningful to study the permeability characteristics of double porous media material combination. Based on the Poiseuille equation, the permeability model of double porous media material combination (DPMMC model) is constructed by using the derived additional stress between porous media materials and the effective stress. The DPMMC model is verified by the test results under different conditions, and the influence of different parameters on the permeability ratio is analyzed. Under different cover loads, water storage pressure, initial porosity and elastic modulus, using the established DPMMC model, the permeability characteristics of coal-mortar combination (grouted area) and residual coal pillar (non-grouted area) composed of coal pillar and mortar are simulated and analyzed. The results show that the DPMMC model can verify the permeability change of double porous media material combination. The permeability ratio of the composite material decreases as the initial porosity ratio coefficient declines, whereas it increases as the elastic modulus ratio coefficient, Poisson’s ratio ratio coefficient, and Biot coefficient ratio coefficient decrease. This research holds significance in evaluating the long-term operation and stability of underground coal mine reservoirs.</p>