Feasibility study on steel slag substitution for offshore hydraulic concrete aggregates is conducted for the resource utilization of steel slag. The steel slag concrete ratio design is carried out by partially replacing natural coarse and fine aggregates with Baosteel roller slag，and various properties of steel slag concrete are studied through indoor tests and pilot project applications. The results indicate that with the increase of the portion of steel slag，concrete slump decreases gradually，the compressive strength，impermeability grade，and abrasion index increase，the electric flux and diffusion coefficient increase slightly，and the chloride resistance deteriorates slightly，and it can meet the quality requirements for the concrete applied in offshore hydraulic structure. The surface quality of the concrete applied in the pilot project is the same as that of the ordinary concrete，and the structural strength meets the design requirements，which provides a new way for the disposal and utilization of steel slag in coastal areas.