In view of the pollution of Cr（Ⅵ） in the groundwater of a contaminated site, we studied the removal rate of Cr（Ⅵ） by four individual agents and four compound agents by single variable method. The effects of extraction concentration, dosage of reagent, dilution ratio of reagent and acid addition on the in-situ remediation of groundwater were discussed, and the reaction products were analyzed by scanning electron microscopy and X-ray diffraction. The results showed that the best remediation effect was obtained when the molar ratio of calcium polysulfide to Cr（Ⅵ） was 2∶1. The concentration of Cr（Ⅵ） in the sand particles from the site aquifer showed a linear distribution after leaching with polluted water of different concentrations. Each cubic meter of Cr（Ⅵ） contaminated aquifer of the site(leached at 100 mg/L) required 1.65 L of 0.29×106 mg/L calcium polysulfide to achieve total remediation. The dilution ratio of calcium polysulfide had little effect on the removal rate of Cr（Ⅵ）; however, the addition of acid can promote the reduction of Cr（Ⅵ） by calcium polysulfide. The reaction products of calcium polysulfide with Cr（Ⅵ） included hydroxyapatite and elemental sulfur. This study shows that the combination of citric acid and calcium polysulfide has a good effect on the remediation of the Cr（Ⅵ） contaminated site, but the reaction products may have a certain influence on the permeability of the site aquifer.