A numerical model of the dynamic triaxial test of graded crushed stone was established based on DEM (Discrete Element Method) to study its dynamic characteristics. The influence of test conditions on simulation results was analysed through numerical simulation. A method for determining the test conditions was proposed, and the reliability of the simulation was verified. We studied the accumulation rule and failure standard of permanent deformation. We then determined the critical failure stress level. The prediction model of permanent deformation cumulative failure was then established. When the calculation time step is greater than 1E-4 s per step, the stability of the dynamic triaxial numerical test of graded crushed stone is good. The plastic deformation of the simulated specimen tends to be stable under 10,000 dynamic loading cycles. When the specimen height and diameter are greater than 20 and 10 cm, respectively, the specimen size has little influence on the simulated axial strain. The recommended specimen size is 10 cm (Ф) × 20 cm (h). The action time curve results are consistent with indoor measurement results, which proves the simulation's reliability. The critical failure stress is approximately linearly correlated with the confining pressure, and the cumulative failure equation of plastic deformation is established.