Abstract: Taking No.2 coal seam of Chiyu Coal Mine as the research object, the grey correlation analysis method was used to predict the drilling cuttings quantity S and gas desorption index of drilling cuttings Δh₂ (the "two indicators") and to determine the sensitivity between the "two index" and the possibility of outburst of No.2 coal seam; combined with "three rate method"(predicted outburst rate, predicted outburst accuracy rate, predicted non-outburst accuracy rate), the prediction index of outburst risk was analyzed and the critical value was determined; the "three rate method" was used to analyze the "two indicators" and verify the validity of the critical value. The results show that: grey correlation degree P(S)=0.909>P(Δh₂)=0.896, the S is more sensitive as a predictor; the critical values of S and Δh₂ are determined to be 7.4 kg/m and 200 Pa, respectively. The field effect test shows that the critical value of the prediction index of No.2 coal seam outburst risk is reasonable