A new detoxification process of chromite ore processing residue（COPR），which utilized the residual chromite ore（Fe，Mg）（Cr，Fe）2O4 in COPR to react with the Cr2O72- in it in an acid environment was proposed on the basis of the systematic analysis and characterization of the composition of COPR.The results indicated that the mechanical grinding played an important role in the new detoxification process of COPR，and the corresponding particle size was at 6~16.5 μm.The optimized detoxification conditions were as follows：the mass fraction of sulphuric acid was 5%，the liquid?鄄to?鄄solid ratio was 4 mL/g，the reaction temperature was 80 ℃ and the reaction time was 60 min. Under the conditions，the mass fraction of the Cr（Ⅵ） in COPR could be reduced to less than 2.5×10-5 after detoxification.