The invention discloses a grouting experiment system for prefabricating a cracked rock mass under excavation stress and a using method. The system is based on a hydraulic fracturing technology, a mining stress field generated in excavation in an actual stope is considered, a complete large rock mass test sample manufactured by a rock mass is prefabricated into the cracked rock mass under the excavation stress, and then a grouting experiment is performed. Hydraulic fracturing is implemented at the top end part, and graded servo control loaders are arranged on the left side and the right side and at the bottom of a rock, so that the purpose of applying different loads on the rock mass in different directions is achieved, the direction of the maximal main stress born by a rock sample is changed by using the relation between hydraulic pressure and lateral load stress, and cracks are generated randomly in the rock mass. Besides, a grouting hole is drilled along a fracturing drill hole, theexperiment is completed by grouting the cracked rock mass, and an experiment basis is provided for analyzing the slurry diffusion rule and slurry-rock mass stability. The grouting experiment system issimple in structure, the experiment design is reasonable, the use is convenient, the cracked rock mass is efficiently and feasibly produced, and the grouting experiment is convenient and easy to implement.