Electrochemical parameters of Cr2 (SO4)3 on Pb and Pb-PbO2 electrode in 1.0 mol/L H2SO4 were measured by cyclic voltammetry, respectively. Dual-chamber diaphragm cell, with Pb-PbO2 electrode as the anode, was used to electrochemical oxidation. The optimum conditions of electro-oxidation process were listed as following: 5% H2SO4 as cathode liquid, 5 A/dm2 anode current density, 7.5 h constant current electrolysis. The conversion of Cr3+ was 25.97%, and current efficiency was 68.45%. After being treated, the content of Cr6+ in ageing liquid was recovered to the effective range. The effect of colored stainless steels treated in the regenerated liquid was consistent with those treated in freshly prepared coloring liquid.