This paper discusses the construction technology of directional slip blasting compaction treatment for the foundation of suspended breakwater from the riprap loading of dike head, parameter selection of blasting compaction, circulation measurement control, as well as tamping compaction of both sides, which is under deep and thick silt ( > 28 m ) conditions of sea area. Monitoring through volume equilibrium method, settlement observation, and drilling exploration, the blasting compaction quality is guaranteed, and the engineering is characterized by short construction period, low cost and small settlement. Thus the technology is worthy of popularizing in similar engineering.