High value-added utilization of solid wastes is one of the important ways of sustainable development. A novel pore size-controlled alkali-activated steel slag-based cementitious material (PASSCM) was synthesized by adjusting the content of pore forming agent of acrylic resin emulsion. Meanwhiel, a new type of porous steel slag-based catalyst loaded CeO2 was prepared via incipient wetness impregnation method in the paper. The composition, structure and optical properties of photocatalysts were characterized with XRF, XRD, BET and UV-Vis DRS. Meanwhile, the photocatalytic performance of hydrogen production from water was evaluated. The results showed that adding pore-forming agent changed the pore structure and the mesoporous volume increased by 70.27% of alkali-activated steel slag-based cementitious material. The mesoporous volume increased by 144.14% in photocatalyst loaded 8 Wt% CeO2. In the simulated solar source irradiation for 6 h, the photocatalyst loaded 8wt%CeO2 exhibiting the highest photocatalytic hydrogen production activity (7 653 μmol·g-1) and hydrogen generation rate ［1 275.5 μmol·(g·h)-1］, which were attributed to mesoporous volume increases the mass transfer rate of the water molecules, and in the formation of the coupled semiconductors, the high dispersion of the CeO2 active component and the FeO in the carrier promoted the high efficiency separation of the photogenerated electron-hole pairs.