Abstract: Large difference of gas emission characteristics between fully mechanized mining and slice mining exists in high gas and thick seam, according to the problem of gas emission during fully mechanized mining, by taking Yangquan 5th mine as research object, based on ventilation and gas data collected in field, gas emission characteristics of fully mechanized mining face was analyzed, and its reason was studied using gas deposit law and fracture evolution law of overlying strata, therefore, gas emission law of fully mechanized mining face was made clear, based on this, gas prevention technology of fully mechanized mining face was summarized and analyzed, tail roadway was set building “U+I” ventilation mode to control gas in upper corner, and strike high-bleeding roadway in up near seam was set for pressure-released gas emission, quantity of drainage reaching 100 m3/min and drainage rate reaching 90%, this provides technical support for gas control of high-gas mining-coal bed and adjacent layer in fully mechanized mining face.