Abstract: Using static experiment method, considering the research cost and environmental protection requirements, six kinds of low-cost and biodegradable leaching agents of citric acid, oxalic acid, fulvic acid, water, rhamnolipid, and tartaric acid were elected to leach and repair high mass ratio Cr contaminated soil. Firstly, the effects of different aging time of Cr in soil on the leaching efficiency were investigated. Secondly, the leaching agent was screened and the leaching conditions were optimized. Finally, a variety of mixed leaching combinations were investigated to determine the best leaching agent combinations. The results show that the Cr aging time has little effects on the total Cr removal rates, but  has significant effects on the removal rates of Cr（Ⅵ）. Different leaching agents have different leaching effects on total Cr and Cr（Ⅵ）, but oxalic acid and citric acid can effectively remove total Cr and Cr（Ⅵ）. The optimal leaching condition of removing total Cr and Cr（Ⅵ）is 0.5 mol/L of oxalic acid or citric acid, m(solid)∶V(liquid)=1∶10, and leaching one time. Under the optimal leaching condition, the removal effect on Cr in  soil is better.

Key words: chromium, soil, leaching agent, leaching condition, mixed leaching