Effect of dynamic compaction method in silty fine sand ground with high fines content is uncertain.The effective reinforcement depth of dynamic compaction in hydraulic filled sand and natural sand is also different.The characteristics of hydraulic filled silty to fine sand are studied in a typical project，and in-situ trial construction is carried out for compaction energy of 5 MN·m.Verification results including standard penetration test，cone penetration test and plate loading test of the whole site after dynamic compaction are analyzed.The results show that dynamic compaction is applicable in hydraulic filled silty to fine sand with average fines content of 22.7%.The effective reinforcement depth of 5 MN·m dynamic compaction is about 11 m，which is much larger than that proposed in standard JGJ 120—2012.Requirements for characteristic bearing capacity of ≥150 kPa，compression modulus of ≥10 MPa can be satisfied after dynamic compaction，and also the standard for liquefaction resistance under seismic fortification intensity of 7 degrees can be met.When thin layers of cohesive hydraulic fills existing above sandy hydraulic fills，the adverse impact on treatment effect can be minimized by filling the craters with sands during compaction.Good effect can be achieved by dynamic compaction in hydraulic filled silty to fine sand with high fines content.The correction factor of effective reinforcement depth of dynamic compaction can be taken as 0.49.