The invention discloses a numerical method for a graded crushed stone dynamic triaxial test. The numerical method comprises the following steps of: simulating the graded crushed stone dynamic triaxial test through establishing a physical model and a mechanical model by using a PFC2D software platform, wherein the simulation operation comprises test of basic parameters, simulation of a test model and generation of a graded crushed stone simulation specimen; secondly, giving micro mechanical parameters to the physical model, and constructing the mechanical model; and then, carrying out repeated dynamic load simulation on the graded crushed stone simulation specimen so as to obtain a graded crushed stone stress-strain curve and a graded crushed stone permanent deformation-loading frequency curve. According to the numerical method disclosed by the invention, the graded crushed stone permanent deformation-loading frequency curve in a triaxial test can be reproduced accurately, conveniently and quickly, and a graded crushed stone deformation rule is disclosed, so that the graded crushed stone fracture mechanism is favorable to research intensively; and the problems of high instrument price and inconvenience for operation in an indoor dynamic triaxial test are avoided, so that the test efficiency is improved, and the research cost is saved.