Abstract: The electro-chemistry behaviors of acid chrome blue and alizarin red in the electrolysis cell have been investigated by IR and cyclic voltammograph to explain the reaction system of Fenton reagent in this paper.Hydroxyl radical is formed in the cell by the following reaction between electro-generated H₂O₂ and Fe²⁺,which is dissolved from the anode.The electro-generated Fenton reagent will oxide the organic dyes and break the—N＝N—double bond.IR result indicated that acid chrome blue is decomposed into two parts of naphthylamine and phenol-aminobenzenesulfonate,then coprecipitated with Fe(OH)\-3.Both of the degradation and decolorization of dyes are efficient.Decolorization and COD_crremoving rate of dyes are decreased in the first 15 min in the cell.When the electrolysis was carried out for 1 h,the decolorization rate reaches 98% and the COD_cr removing rate approaches 80%.