Porous geopolymer materials were prepared with steel slag as the main raw material, water glass as the activator and H2O2 as the foaming agent. The raw materials and final samples were characterized by XRD, FTIR, SEM and BET. The effects of calcium silicon ratio, activator and H2O2 admixture on the properties of the material were studied. The porous geopolymer was used as adsorbent to investigate the adsorption effect of Cu2+. It shows that when the calcium-silicon ratio is 1.0, water glass mixing is 20.4% (mass fraction) and foaming agent mixing is 4% (mass fraction), the material performs well, with 86.4% total porosity, 0.5 MPa compressive strength, 0.408 g/cm3 volume density, volume water absorption rate is 56.31%, and steel slag utilization rate is 65.85%, significantly improving the specific surface area and pore capacity. The adsorption results show that the material has a good adsorption effect on Cu2+, the removal rate reaches 91.44%, and the equilibrium adsorption amount reaches 15.239 mg/g. The adsorption process conforms to the pseudo-second order.