煤层透气性系数是衡量煤层瓦斯流动难易程度的关键参数。现行的煤层透气性系数计算式中，将变压力非线性偏微分方程的系数假定为常数，理论推导结果存在较大缺陷，使得现场测定的透气性系数存在较大偏差。为解决煤层透气性系数测定失准的问题，推导了钻孔径向流量法测试煤层透气性系数的过程，并在推导过程中指出该方法存在的问题。以朗格缪尔式瓦斯含量和达西定律为基础，建立无量纲模型，将模型解算结果进行反演拟合，得到新的煤层透气性系数计算式，并通过现场实测钻孔数据进行验证，修正了现行的煤层透气性系数测试方法，提出准确可靠的计算煤层透气性系数的新方法。结果表明：用抛物线式表示煤层瓦斯含量并将变量煤层瓦斯压力p^1.5视为常量推导而来的煤层透气性系数计算式，相当于将瓦斯含量拟合成与压力平方成正比关系，理论与实际测算均存在较大误差。采用朗格缪尔式无量纲模型计算出的无因次瓦斯涌出速度Y'进行反演拟合，可解决现行计算方法的缺陷；当吸附常数b与原始瓦斯压力p₀的乘积(无因次原始瓦斯压力)不同时， Y'与无因次时间Fo'的函数曲线明显不同，由此得到了含有无因次原始瓦斯压力的透气性系数计算式；当煤层和钻孔条件一定时，由不同时间测试的瓦斯涌出量计算得到的煤层透气性系数λ值具有良好的再现性。新的煤层透气性系数现场测定方法与现行方法完全相同，不增加额外工作量，但新方法的计算更加精确可靠。

The permeability coefficient of coal seams is a key parameter that judges the difficulty of gas flow in coal seams. In the current calculation formula for the permeability coefficient of coal seams, the coefficient of the nonlinear partial differential equation with variable pressure is assumed to be a constant, which leads to significant errors in the theoretical derivation results and results in significant deviations in the permeability coefficient measured on site. To solve the inaccurate determination problem of the coal seam permeability coefficient, this paper derived the process of using the radial flow rate method to test the coal seam permeability coefficient, and pointed out the problems of this method during the derivation process. Based on the Langmuir's gas content and Darcy's law, a dimensionless model was established, and the model solution results were inverted and fitted. A new calculation formula for the coal seam permeability coefficient was obtained, which was verified by on-site drilling data. The current testing method for coal seam permeability coefficient was revised, and an accurate and reliable new method for calculating the coal seam permeability coefficient was proposed. The results indicate that using a parabolic equation to represent the coal seam gas content and treating variable p^1.5 as a constant to derive the coal seam permeability coefficient calculation formula is equivalent to fitting the gas content into a proportional relationship with the square of pressure. There are theoretical problems and significant errors in actual calculations. Using the Langmuir dimensionless model to calculate Y' for inversion fitting can solve the shortcomings of current calculation methods. When the product of the adsorption constant b and the original gas pressure p₀ (the dimensionless original gas pressure) is different, the function curve of the dimensionless gas emission velocity Y' and the dimensionless time Fo' is significantly different. Therefore, the permeability coefficient calculation formula containing the dimensionless original gas pressure was obtained. When the coal seam and drilling conditions are constant, the values of the coal seam permeability coefficient λ calculated from the gas emission volume at different times have a good reproducibility. The new on-site measurement method for the permeability coefficient of coal seams is completely the same as the current method without adding additional workload. However, the new calculating method is more accurate and reliable.