This paper focused on the macro-meso mechanism of the dynamic response of dynamic compaction in granular soils based on its discrete nature. A three-dimensional discrete element model was first established to simulate the dynamic compaction process by means of secondary exploitation by using the particle code PFC3D and the numerical results were compared with the laboratory model tests. The validation of this numerical approach allowed the extended study of the dynamic response of the tamper and soils and the particles movement. The results show: 1) the dynamic stress propagates within a certain zone and there is a lag in the onset of the peak value along the depth;2) the dynamic stress attenuates more rapidly in the horizontal direction than in the vertical direction; and 3) the particles beneath the tamper mainly move vertically, while the particles below the tamper corners mainly move obliquely downward and the particles side of the tamper move horizontally or obliquely upward. The findings of this study provide a new route for the study of the meso-mechanism of granular soils improved by dynamic compaction.