To determine the optimal number of dynamic compaction for reinforcing the soil foundation in the third phase expansion project of a certain airport, and evaluate the reinforcement effect of dynamic compaction method for the filling, this study simulated the process of dynamic compaction by establishing a finite element model. After analysis, the numerical and cumulative settlement values for each point during point compaction and full compaction were obtained. Based on the simulation results, the variation pattern of settlement rate with the number of compaction for both compaction methods was determined. According to the field test plan, the dynamic compaction test was carried out at the selected site. The experimental data were used to validate the numerical simulation results. The function expression of settlement rate was revised twice, and the modified functional relationship was determined. Numerical simulations and field test results indicate that the patterns and conclusions obtained from the two methods are consistent. Therefore, reference to the design plan for the dynamic compaction reinforcement of soil foundation, the number of compaction for the first and second point compactions should be controlled at 8 to 9 times, and the number of compaction for the third full compaction should be controlled at 5 to 6 times. This ensures the contribution rate of the ramming to the compaction in the process of dynamic compaction, resulting in a well-reinforced soil foundation, and provides reference for future related projects.