Abstract: The phenomenon of blowout from drilling hole tends to occur during the extraction hole construction in outburst coal seams, which frequently results in the gas concentration overrun in drilling roadways and even the wounding accidents created by the blowout coal. The blowout preventer is the main equipment to prevent blowout accidents, and the orifice device is its key part．This paper proposes a multi-orifice blowout preventer which is of double brush structure. Through the analysis of interior pressure field, dust transport features and gas concentration field and combining the airflow characteristics of each export during the blowout from drilling hole, its application is discussed. The result indicates that this device is effective in preventing the blowout from drilling hole for coal seams with a gas pressure less than 2 MPa.