Abstract: In order to accurately determine the size of coal seam gas extraction radius, through the analysis of the characteristics of the existing measurement methods and the operability of the measurement process, it is found that a single index or a single method can't meet the requirements of extraction radius inspection. Considering the gas content and the pre-drainage rate as the evaluation index, the method of combining the Gas Reserves Method and the numerical simulation is used to investigate the extraction radius, and it is applied in the 3# coal seam of Gaohe Coal Mine. This method is obtained by examining the extraction radius of No. 3 coal seam in Gaohe Coal Mine. When the extraction radius is 1m, 1.25m and 1.5m respectively, the extraction compliance time is 57d, 70d and 76d; Using multiple indicators and multiple methods to examine the extraction radius is a method that can effectively measure the extraction radius, which can obtain the corresponding extraction radius at any time and has strong operability.