As a solidified material, iron salt has a good effect on the remediation of soil antimony （Sb） pollution, but its improper use will cause soil acidification and reduce the remediation effect. The ferric sulfate cornerstone ash-reinforced passivation material （FS） and the polyferric sulfate cornerstone ash-reinforced passivation material （PFS） were prepared by using ferric sulfate, polyferric sulfate, and quicklime as raw materials. The morphology and characteristics of the materials were analyzed using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and Fourier transform infrared spectroscopy （FTIR）. The adsorption mechanism and remediation effect of the two materials on soil Sb were studied by an adsorption experiment and a soil culture experiment. The results showed that FS and PFS were mainly composed of iron and calcium oxides and hydroxides, which contained hydroxyl, carbonyl, and other functional groups. The Freundlich model fitted the isothermal adsorption data well, indicating that the adsorption of Sb （Ⅲ） by both materials was multilayer adsorption. The adsorption capacity of Sb （Ⅲ） by FS and PFS increased with the increase in materials added. The pseudo-second-order kinetic model fitted the adsorption kinetics of FS and PFS well. Among the coexisting ions, PO