Abstract: In this study, we investigated the decolorization of the crystal violet, indigo carmine and reactive black KN-B by a laccase-mediator system. The mediator system was composed of laccase from Cerrena unicolor LS0547 and the mediator of violuric acid (VA) or acetosyringone (Ace). The effects of initial pH, temperature, dye concentration and the dosage of laccase on the decolorization of dyes were tested. The results showed that the decolorization of indigo carmine and reactive black KN-B was remarkably improved in the presence of Ace, while crystal violet was more efficiently decolorized with the addition of VA. The decolorization rate of crystal violet reached 95.42% at pH 4.0 and 50 ℃. Indigo carmine could be decolorized with a rate of 99.86% at 40 ℃, which was not affected by pH. And 92.38% of reactive black KN-B was decolorized at pH 6.0 and 40 ℃. Therefore, the C. unicolor laccase-mediator system has a potential application in the treatment of industrial dye wastewater.