Abstract: Based on the drilling natural gas flow attenuation theory, combined with the field datum of drilling natural gas flow in Yangcheng mining area 3^# coal seam of Shanxi Jincheng, the flow dadum of drilling natual gas flow measured during 1～ 65 d different time periods are counted, the attenuation coefficient during different time periods are compared through regression analysis, and then the shortest effective time of drilling natural gas flow attenuation coefficient α is measured and discussed according to the fitting degree of decay curve. The results show that the reasonable measured time of attenuation coefficient in anthracite layer with larger drilling natural gas flow should be 40 d.