Abstract: The dynamic evolution mechanism of gas explosion pressure drop is the basis of theoretical and field application research of point type gas fracturing coal seam permeability increasing technology. The experimental results show that the pressure time history trend after the gas explosion is triggered generally presents a rapid rise and a nonlinear decline; due to the coupling effect of the non-uniform gas ejection and the noise of the piezoelectric sensor itself, the local irregular and unsteady pressure fluctuation occurs. It is found that the gas explosion port has the fastest rate of pressure rise, and the time and distance between the gas explosion port and the gas explosion port increase slowly after a rapid increase, which shows a power-law of pressure rise as a whole; the gas explosion port is the peak pressure area, and the gas explosion pressure decreases with the increase of distance from the gas explosion port, which shows a quadratic parabola of unsteady pressure drop as a whole.