Goafs are composed of large, irregularly shaped broken rocks. This means in order to calculate the permeability and inertial resistance coefficient of a goaf, the Ergun equation must be modified. The coupling relationships between coefficients A and B, and particle size and porosity are established based on the existing simulation research. Coefficients A and B both have a quadratic polynomial relationship with porosity. The quadratic polynomial's constant term ratio has a good power function relationship with particle size, while the linear term ratio and quadratic term ratio both have good exponential function relationships with particle size. By introducing the shape factor of permeability and inertial resistance coefficient, which are calculated by dividing the experimental value with the theoretical value, the correction model is established for the permeability and inertial resistance coefficient of the goaf. The permeability and inertial resistance coefficient shape factor have good power function relationships with particle size. (c) 2021 Elsevier B.V. All rights reserved. Goafs are composed of large, irregularly shaped broken rocks. This means in order to calculate the permeability and inertial resistance coefficient of a goaf, the Ergun equation must be modified. The coupling relationships between coefficients A and B, and particle size and porosity are established based on the existing simulation research. Coefficients A and B both have a quadratic polynomial relationship with porosity. The quadratic polynomial's constant term ratio has a good power function relationship with particle size, while the linear term ratio and quadratic term ratio both have good exponential function relationships with particle size. By introducing the shape factor of permeability and inertial resistance coefficient, which are calculated by dividing the experimental value with the theoretical value, the correction model is established for the permeability and inertial resistance coefficient of the goaf. The permeability and inertial resistance coefficient shape factor have good power function relationships with particle size.