Abstract: Under potentiostatic mode，the decolorization behavior of amaranth was studied by using activated carbon fiber（ACF）as anode or cathode in a two-compartment cell separated by cation exchange membrane from -0.8 V to 1.4 V（vs SCE）.The relationships between color/TOC/COD removal and potential were investigated.The use of ACF electrode was successful in removing the color，TOC and COD within a proper potential range.The oxidation and reduction potentials of amaranth on ACF electrode were 0.6 V and -0.2 V,respectively.In the range of -0.1—0.5 V，the decolorization resulted from adsorption of amaranth on ACF，and adsorption behavior was scarcely affected by the potential.In the range of -0.2—-0.8 V，the electroreduction of amaranth played an important role in decolorization and followed pseudo-first order kinetics，and the rate constant was a linear function of the potential.TOC，COD were removed by 60% approximately.In the range of 0.6—1.4 V，the electrooxidation of amaranth filled the role of decolorization and followed pseudo-first order kinetics too.About 30% of TOC，COD were removed.