Abstract: In order to solve the problem of outburst prevention in coal roadway excavation in geostress-dominated outburst dangerous soft 3^# coal seam, under the condition of mining without protective layer in Sangshuping Coal Mine, pressure relief as the main treatment measure was proposed and gas drainage was also considered.In Sangshuping Coal Mine, the effect of the water jet reaming and pressure relief extraction test were investigated. The results show that after water jet reaming, the gas flow attenuation coefficient of the drilling borehole is reduced by 65% to 74%, the natural gas emission flow is increased 2 to 3 times, and the extractability of the coal seams has been improved. The crushing coal chip rate combined with the residual gas content are proposed for effect evaluation of outburst prevention effect, the corresponding critical value is determined according to the differentiation of the occurrence conditions of the coal roadway excavation area.The combination of the technology and the evaluation index can effectively solve the problem of outburst prevention in coal roadway excavation in geostress-dominated outburst dangerous soft and thick coal seam of Sangshuping Coal Mine.