Abstract: How to determine the effect of pre-drainage inspection index critical value is one of the technical problems that coal and gas outburst mine should be resolved.According to the coal seam gas geological conditions of Daning Coal Mine,the article analyzed the control action of fault, tectonic coal and gas on No.3 coal seam.According to the relationships between desorption index of drill-cuttings K₁ and gas content of coal seam,using the gas content measurement technology,and combined the statistical analysis method and outburst prevention practice experience for many years at home and abroad,the article determined that the effect of pre-drainage inspection index critical value is 9 m³/t in normal area of No.3 coal seam,and the index critical value is 7 m³/t in tectonic anomaly area.