Abstract: In order to find a way to accurately measure drainage radius of the low-permeability soft coal effectively,and to determine the reasonable drilling drainage parameters,based on the coal medium’s double-porosity structure characteristics and the gas flow theory,according to the law of conservation of mass,Fick’s law,and Darcy’s law,establish the gas flow model to consider the diffusion- seepage action.Take the industry low-permeability soft 3# coal seam of the Yuwu coal mine for example,implant the established gas flow model into the COMSOL to carry out the calculation,we will get the gas flow regularity surrounding the drainage drill hole and the effective drainage radius of the different drainage time.calculating date consistent with the field test results confirm he validity of the established gas flow model,and form a way of accurately determine the low-permeability soft coal seam surrounding’s gas flow regularity and drainage radius.