The invention aims to solve the problem of falling of mountain stones, and discloses a mountain stone stability testing device. Themountain stone stability testing device comprises a sleeve, an anti-skid layer is sleeved with the sleeve, a hydraulic cylinder is fixedly mounted on the side face of the sleeve, a piston rod is mounted on the upper side of the hydraulic cylinder, and a baffle is fixedly mounted at the upper end of the piston rod. A positioning ring is fixedly mounted on the right side of the lower surface of the baffle; a water spraying pipe is arranged in the positioning ring in a sleeving manner;a water pump is fixedly installed on the right side face of the sleeve, a liquid storage tank is installed on the right side face of the water pump, a connecting pipe is connected between the liquid storage tank and the water pump, and connecting frames are symmetrically connected between the liquid storage tank and the water pump; an end cover is arranged on the liquid storage tank, and a sliding frame is fixedly arranged on the lower side face of the liquid storage tank. By controlling the telescopic frame, the distance between pedestrians can be controlled, then the impact force of the water pump is used for carrying out an impact test on stones on a mountain, the stability of the stones on the mountain is observed, and a guarantee is provided for the safety of tourists.