Caofeidian southeast breakwater phase II, the first protecting building of the Caofeidian industrial zone, is not only an important part but also a protection of the industrial zone. Through analyzing the tide and the dynamic topography of the engineering region, it is concluded that the construction of this project has little effect on the Caofeidian groove. The building level for this project is designed as Level I, the structural section is sloping structure, and the breakwater core is the riprap structure. The breakwater structure adopts double mounds: riprap for the sea side and sand bags for the land side, with fill sand in the middle. The closure engineering is the key for the implementation of this project. This article describes the exterior condition for the closure engineering and the closure construction technology.