The invention discloses a coal mine impact ground pressure monitoring device and a monitoring method. The device comprises a pressure bearing shell and a limiting cylinder, the upper surface of the pressure bearing shell is of an arc-shaped structure, the inner portion of the pressure bearing shell is provided with a limiting frame, a sleeve penetrates through the surface of the limiting frame, the middle of the outer surface of the sleeve is wrapped by the end of a transmission chain, the two ends of the sleeve are provided with guiding rods, a limiting cylinder is mounted on the outside of the sleeve, the inner surface of the limiting cylinder is engaged with a sliding groove, two grooves are formed in the side surface of the pressure bearing shell, the ends of the guiding rods are located in the grooves, and the lower portions of a cavity and the pressure bearing shell are provided with pressure sensors. According to the coal mine impact ground pressure monitoring device, in the initial state, the ends of the guiding rods are in the grooves, so that when the pressure bearing shell sinks in the well, the ends of the guiding rods do not collide with an obstacle, and when the sleeve rotates, the guiding rods conduct parallel movement, which allows the guide rods to contact the surrounding soil to improve the accuracy of the data.