Abstract: To explore the influence of fracture structure on mechanical properties of rock mass, compression simulation experiment were carried out on rock samples with prefabricated fractures. Based on SEM, NMR and Vic-3D technology, multi-scale study was carried out on rock mass in combination with acoustic and macro-meso-structural characteristics. The rock sample strength decreases with the increase of fracture length, penetration and number, and decreases first and then increases with the increase of fracture dip angle. The rock sample strength of 30 mm fracture is the lowest, and the rock sample strength of 90° fracture is closest to the intact rock sample. Tensile failure occurred in intact rock samples, 0° and 90° fracture samples and tensile and shear composite failure occurred in rock samples with different fracture penetration degrees. Shear failure occurred in rock samples with different fracture lengths, numbers, 30°, 45° and 60° fractures. After loading, the proportion of micro pores decreases while that of medium and large pores increases, indicating that the initial damage and loading caused by prefabricated fractures can change the internal pore structure of rock samples, thus affecting its macroscopic mechanical properties.