An innovative test equipment for analyzing the dynamic damage at the interface of geosynthetic materials is introduced. It provides a result of shear damage on the structural surface of a geosynthetic material that has been subjected to cyclic loading of different amplitudes. First, the experimental data of geosynthetics under cyclic loading are obtained based on the innovative test equipment mentioned above, and a mathematical identification method for the relationship between cyclic loading parameters and shear mechanical behavior of geosynthetics is proposed based on the Mohr-Coulomb criterion, assuming that the micro-element strength of geosynthetics follows Weibull distribution. Moreover, the proposed model, which takes into account repeated loading-unloading conditions, enables this simulated damage process to have properties of reoccurring load cycles, and the proposed method was evaluated by experimental datasets from this study and the existing literature and proved to have a satisfying performance in predicting mechanical behavior of shear stress in geosynthetics under different cyclic loadings. Second, the self-developed test instrument can well solve the direct shear parameters of geosynthetics under dynamic load and can be obtained as a new dynamic statistical model with rate-dependence in interface damage.