Abstract: The fracture characteristics of real rock mass under impact load are simulated by using the half-disk defect medium containing prefabricated double lays.The experiment shows that when the angle between the lamination plane and the prefabricated crack is taken as a variable, the reduction of the angle will hinder the crack growth.The specimens with 60° pass through two laminations, while the specimens with 45° pass and 30° fail to pass through the second lamination plane, and the offset after the first lamination plane of the three-crack growth is 20.6 mm, 32.3 mm and 26.6 mm respectively.Three kinds of specimen cracking in front of the crack has not extended to bedding only affected by the type Ⅰ stress intensity factor, the main tensile stress cracking, cracking mechanism is complicated, in the late by two kinds of stress intensity factor, and in the layered rock mass, the bedding surface structure is relatively weak, easy occurrence crack under impact load.The research results have important reference value for the study of structural strength of intermediate rock mass.