Abstract: To study the shock vibration mechanism of super structural testing machine caused by brittle fracture of specimen, a scale model test was carried out on the main machine of a multifunctional structural load system. The influence of the specimen brittleness, the specimen bearing capacity and the testing machine stiffness on the vibration of the testing machine was analyzed. The experimental results show that the vibration response of the testing machine is most significant at the lower beam. The vibration response of the testing machine increases with the increase of the specimen brittleness, increases with the increase of the specimen bearing capacity, and decreases with the increase of the testing machine stiffness. This paper provides a test basis for the numerical simulation of the testing machine vibration, and has certain reference significance for the vibration reduction design of the super structural testing machine.