In the construction process of hydraulic slag discharge elevation drilling in the bottom drainage roadway, with the increase of drilling depth, the return time of the drill pipe is too long, and a large amount of high-concentration gas is ejected from the tail of the drill pipe during the return process, causing abnormal gas increase or gas overrun accident. In addition, during the period of coal crossing and hydraulic punching, the waiting time of the drill pipe returning water will also appear buried drilling accidents such as drill pipe locking, which will increase the cost of gas control. In order to solve this safety hazard, taking the cross-layer drilling project in the mining area of 21114 fully mechanized mining face in Yungaishan mining area as the research object, according to the characteristics of the elevation angle drilling in the bottom pumping roadway, the anti-backwater device of the drill pipe is innovatively designed. The practice shows that the device effectively solves the problem of water accumulation and gas emission from the tail of the drill pipe in the upper part of the anti-backwater device during the period of adding the drill pipe, which ensures the safety of the drilling operation and improves the work efficiency.