Based on the FLAC software,a three-dimensional model is established.The effects of different tamping energy and tamping times number on the dynamic compaction are simulated.The changes of the Young’s modulus before and after the dynamic compaction are analyzed.The results show that the thickness of the sand layer and the distribution of the soft soil layer on the surface play a great role in determining the tamping energy.For the lower lying loose sand layer,the depth and effect of treatment can be increased by increasing the tamping energy and times (7～8).For the lower lying soft clay layer,the reinforcement effect can be improved by reducing the tamping energy and increasing the tamping times.After tamping,the Young’s modulus of the surface blowing sand is greatly improved,from the original 10 MPa to 20～40 MPa.