Alkali-activated steel slag-slag pervious concrete (ASSPC) was prepared by using steel slag-slag composite powder instead of Portland cement and steel slag aggregate instead of natural aggregate. The compressive strength of ASSPC under different factors was studied, and the microscopic properties of hardened cementitious materials and interfacial transition zone (ITZ) of ASSPC were characterized by XRD, TG, FESEM and SEM-EDS. The effects of cementitious materials on the development of mechanical properties of ASSPC and its influence mechanism were clarified. The results show that ASSPC has high early compressive strength. With the increase of steel slag-slag ratio, the compressive strength increases first and then decreases. Using steel slag as aggregate to prepare pervious concrete effectively optimizes the microscopic properties of ITZ and improves the mechanical properties of ASSPC. With the increase of water-binder ratio (0.24～0.32), the compressive strength of ASSPC increases first and then decreases.