Abstract: In order to study the influence range of hydration reaction heat release of coal seam expansion permeability enhanced material on coal mass, the expansive pressure of the expansive material and the change of reaction temperature with time were measured by self-made test device. The temperature change and influence range of coal mass around the borehole were analyzed by numerical simulation when the expansive material was heating up and cooling down. The results show that the maximum expansion pressure generated by the hydration reaction of permeability enhanced material of coal seam expansion is about 47 MPa, and the maximum hydration temperature is 103.5 ℃; the temperature change of expansive material can be divided into four stages, namely slow temperature rise, rapid temperature rise, accelerated temperature rise and cooling; under the condition of expansion borehole with a diameter of 100 mm, the radius of the coal subject to the temperature of the expansive material can reach 1.2 m, which can effectively increase the molecular kinetic energy of gas within this range, accelerate gas desorption and improve gas extraction efficiency.