Abstract: The C₂ coal seam in the No.1 well of Bailongshan Coal Mine is an outburst coal seam. In order to improve the effect of mine gas drainage, ensure the safety of cross-cut coal uncovering and shorten the period of coal uncovering, an experimental study on antireflection and extraction promotion technology of hygraulic flushing in hole was carried out. The research results show that after adopting the measure of hygraulic flushing in hole for cross-cut coal uncovering, the coal output of C₂ coal seam with low permeability and relatively soft coal is larger, the coal output from single hole is between 1.27 t and 2.73 t, the average coal output is 2.28 t; after 210 d of continuous drainage in the test area, the coal seam gas content decreases from 11.465 9 m³/t to the rang of 3.551 1 m³/t to 4.251 7 m³/t, with a decrease of about 63%, and the gas pressure decreases from 0.81 MPa to 0.34 MPa, with a decrease of about 58%; during coal uncovering, the maximum value of gas desorption index of drilling cuttings is 0.32 mL/(g·min^1/2), the maximum value of drilling cuttings is 2 kg/m, the gas concentration after blasting is from 0.04% to 0.24% and the gas emission is 2.22 m³/min. The measures of hydraulic flushing in hole can provide technical support for the safe and rapid coal uncovering at cross-cut in mine. It plays an important guiding role in production safety.