Abstract: The remediation of chromium-polluted sites has become a key focus in current environmental governance. Five reducing agents were selected for laboratory remediation experiments on typical chromium-contaminated soil. The removal efficiency of hexavalent chromium (Cr(Ⅵ)), optimal dosing conditions and in-situ remediation applicability of different agents were compared. Meanwhile, soil column infiltration tests and chromium speciation analysis were conducted to evaluate the remediation performance of the superior agents. The results showed that among the five reducing agents, ammonium polysulfide achieved the highest Cr(Ⅵ) removal efficiency at 91.30%, followed by calcium polysulfide with a removal efficiency of 77.64%. The optimal dosage ratio tests indicated that when the molar ratio of ammonium polysulfide to Cr(Ⅵ) was 1∶1, the Cr(Ⅵ) removal efficiency reached 94.31%; with further increases in dosage, the removal efficiency remained stable at approximately 95%. By comparison, calcium polysulfide reached a Cr(Ⅵ) removal efficiency of 90.34% at a molar ratio of 2∶1, which was lower than that of ammonium polysulfide. In-situ soil column experiments verified that the infiltration coefficient of ammonium polysulfide solution was higher than that of calcium polysulfide solution, demonstrating stronger migration and infiltration capacity in soil media without easily causing soil pore blockage, thus being more suitable for in-situ remediation. Chromium speciation analysis revealed that the proportion of exchangeable chromium in soil decreased obviously after the addition of ammonium polysulfide, and the stability of chromium was greatly improved. The findings suggest that ammonium polysulfide possesses favorable application potential for in-situ remediation of chromium-contaminated soil.