Abstract: In order to study the impact of negative pressure on the gas extraction process, we proposed the view of negative pressure influence factor β and carry out assignment analysis, and established a number of experimental observation drillings in the same seam with occurrence conditions in different extraction time, through the adjustment of negative pressure of the borehole record including its gas concentration, flow and other factors, analyzing the data, research results show that in early gas drainage of the drilling, negative pressure influence coefficient β is lower, high negative pressure drainage flow is not meaningful to improve drainage concentration and extraction; in the later of the extraction, permeability in coal seam significantly increases, coefficient β value increases; an appropriate increase of the negative pressure drainage can largely increase drilling gas flow, improve the gas extraction concentration of borehole and shorten the cycle of gas drainage.