Based on the explicit dynamic nonlinear finite element analysis method, ANSYS/LS-DYNA was used to analyze the dynamic compaction, and the general steps of explicit dynamic nonlinear numerical simulation method were obtained. Combined with the example of an embankment compaction, a three-dimensional model of the compaction process was simulated to get reinforcement range and fields of stress and displacement. Compared with the field data, this numerical simulation method was proved to be applicable. On this basis, the rammer selection for improving the fly ash embankment in Yueyang by dynamic compaction was studied, and the settlements of soil after dynamic compaction were analyzed and compared, and the results show that the choice of a heavier hammer under the same energy level will have a better reinforcement effect.