To study the influence of the alkaline activator on the performance of steel slag cement, the effects of alkaline activators (water glass、Na₂CO₃/NaOH、NaOH) on the macroscopic mechanical properties of steel slag cement are studied in this article. Further, the microscopic characteristic is investigated by hydration heat release, X-ray diffraction (XRD), thermogravimetric analysis (DSC-TG), scanning electron microscope (SEM) and mercury intrusion porosimetry test (MIP). The results show that the alkaline activators increased the basicity in the early hydration liquid phase of steel slag cement, accelerating depolymerization of steel slag vitreous to produce H₃SiO-₄ and H₃AlO^2-₄, improving the reaction rate, facilitating the formation of C-S-H gel and zeolite products, which is manifested by the shortening of setting time and induction period, the increase of reaction heat, cumulative heat release and early mechanical strength; the influence of alkaline activators on the properties of steel slag cement is related to its molecular structure of activators, and the order of influence was water glass, Na₂CO₃/NaOH, NaOH in descending order; Water glass could increase the alkalinity of liquid phase in steel slag cement, and the SiO^2-₃ could react with Ca(OH)₂ to produce C-S-H gel. The addition of alkaline activators can promote the hydration reaction of steel slag cement, which is helpful to the improvement of the mechanical properties and the compactness of the microstructure of steel slag cement.