Abstract: In the process of gas extraction in Daping Coal Mine, the gas extraction concentration is low and the effective pre-pumping period is short, so it is not good for gas extraction. The research topic of negative pressure optimization for gas drainage is proposed. A comprehensive analysis and test is carried out to determine the negative pressure of the suction hole by combining the attenuation of gas parameters and the attenuation of gas concentration in the hole under different suction pressure. The field test and analysis on 21 upper part of the tunnel show that the negative pressure range of -25 to -35 kPa in the test area of 21 upper part of Daping Coal Mine is reasonable, and the optimum extraction negative pressure is determined to be -30 kPa.