The effective utilization of stainless steel slag on a large scale has posed a persistent challenge. To address this problem, this study used the orthogonal test method to investigate the optimisation of the ratio of stainless steel slag preparation cementitious materials while exploring the curing mechanism of metallurgical solid waste materials and its stability and the leaching of heavy metals. The experimental results revealed that the optimal combination consisted of 59% granulated blast furnace slag(GBFS), 35% stainless steel slag(AODS), and 6% desulfurization gypsum(DG). This composition yielded impressive compressive strength values of 11.40 MPa at 3 days and 28.36 MPa at 28 days. The stainless steel slag(AODS) contains a large amount of highly reactive calcium-containing material, accelerating the hydration reaction for 7–28 days. Moreover, the 3CaO·2SiO2·3 H2O(C-S-H) dense layered structure and related products produced by the hydration reaction can effectively encapsulate the Cr2O3 particles. As a result, the strength, stability and safety of the cementitious materials were significantly improved.