Abstract: In order to study the influence of soaking pressure and soaking time on the permeability of Qiyuan high-rank coal seam during nitrogen injection,the experimental method that simulating the soaking stage of nitrogen injection was adopted,and the related laboratory experimental equipment were designed and assembled,which reproduced the soaking pressure and soaking time on the permeability of Qiyuan high-rank coal seam during nitrogen injection. The variation on the permeability of Qiyuan high-rank coal samples was obtained under different soaking pressure and soaking time. The experimental results show that the permeability of coal sample increases with the increasing of the soaking pressure in the soaking stage of the nitrogen injection process,and there is an optimum value of soaking time:the increase of permeability of coal sample increased with the increase of soaking time in the initial soaking stage,and there would be a sharp decline in the increase of permeability of coal sample after a certain time (48～72 hours).Therefore,increasing the pressure of nitrogen injection has a positive impact on improving the permeability of high-rank coal seams,and there is an optimum soaking time.