In order to determine the sensitive indicators used for forecast of coal and gas outburst in working face,the electromagnetic radiation characteristics of heading face in Yanmazhuang Mine and Xieyi Mine are researched,the intensity of electromagnetic emission(EME) E and the conventional forecasting indexes such as R value and drilling cuttings indexes Δh2,K1 and S were compared.The theory of gray system was used to compare the level of gray correlation degree of the forecasting indexes in order to achieve the optimum selection of indexes.The result indicated that the comprehensive correlation degree of EME index is higher than that of conventional indexes,its accuracy rate in forecasting non-outburst dangerousness is 100%,so it can be used as a primary index of outburst forecast.