Abstract: Aiming at gas outburst problem during crossing hole construction and hydraulic reaming construction process in Liangbei Mine, drawing on the blowout preventer from other mine, according to the high strength of mine gas orifice, uncontrollable of orifice time and other actual conditions, the blowout preventer is improved, and a large capacity high strength gas blowout preventer system is produced, which solves the problems of gas outburst, large quantity of outburst and hard control of gas overrum during crossing hole construction and hydraulic reaming construction period. This effectively improves the underground working environment, and increases the safety factor.The paper also summarizes the advantages and disadvantages of the blowout preventer and points out the place that should be improved further.