Abstract: To reduce the risk of outburst for high gas excavation face in period of mining and increase the permeability of the coal seam, an outburst prevention technique by CO₂ is introduced in Yuwu Coal Company. This technique is carried mainly by the hole located in the working face. On the basis of the original single-hole pre-splitting, controlled pre-splitting in deep hole technique was tested by constructing controlled holes. The experiment proves that the indexes of seam outburst prevention, the uniformity of gas emission and the amount of gas drainage are changed obviously.