Abstract: An in-situ rock mass elastic modulus measurement system includes a controller, a telescopic rod, and a protective barrel; the telescopic rod is fixedly connected to the protective barrel; in-hole supporting structures are arranged at upper and lower ends in the protective barrel which is internally fixedly connected with a base; the base is slidably connected with a feeding sliding plate which is driven by a feeding cylinder and provided with a right-angle transmission diverter, a driving motor, and a grinding cylinder; the diverter is in transmission connection with the driving motor; two ends thereof are connected with grinding pressure heads; the diverter is driven by the grinding cylinder to translate horizontally, and drives the grinding pressure heads to outwards grind a borehole wall; a hydraulic oil cylinder is fixedly arranged on the feeding sliding plate; a displacement sensor is arranged on a cylinder body of the hydraulic oil cylinder.