In order to promote the high-value utilization of iron and steel metallurgical slag and chemical waste slag, steel slag, blast furnace slag, soda residue and desulfurization gypsum were used as raw materials to prepare artificial reef cementitious materials for marine ranching through the combination and synergistic effect between active activator and solid waste materials. By mixing 16% (mass fraction, the same below) steel slag , 64% blast furnace slag, 8% soda residue and 12% desulfurized gypsum, the 28 d compressive strength of the mortar test block reaches 52.6 MPa, which has the potential to replace Portland cement in some cases. The influences of steel slag and blast furnace slag ratios on the compressive strength development of the net slurry test block soaked in seawater of East China sea in the 15 months were studied. Hydration products of the total solid waste cementitious materials system were studied through XRD, SEM and MIP characterization methods. The results show that there is a synergistic hydration between steel slag and blast furnace slag, and the main hydration products are ettringite (AFt), C-S-H gel and Friedel’s salt (FS). The amorphous C-S-H gel, which binds AFt to FS, is the main source of strength of the whole system. The research provides scientific basis for the proper settlement of large amount of solid waste.