Abstract: Based on the large-scale field tests on the vibration velocity caused by dynamic compaction in soil-aggregate mixtures, the propagation and evolution of particle amplitude and waveform in the process of dynamic compaction are analyzed, then the vibration response and reinforcement mechanism of the internal particles in soil-aggregate fills under the tamping energy of 1000 kN·m are studied. The results show that there are only two vibration forms, shock wave and vibration wave, in the soil-aggregate mixtures under the action of dynamic compaction. Then, the concept and method of the critical elastic vibration velocity of soil-aggregate mixtures are proposed, and the corresponding critical elastic vibration values are given. The expansion rules of each area with the times of ramming are given by the evolution laws of spatial vibration velocity. Finally, the reinforcement mechanism of dynamic compaction of coarse-grained soil-aggregate mixtures is expounded, the reinforcement process is divided into four stages, and the guiding suggestions for the layer thickness under dynamic compaction in the construction are proposed.