Abstract: With the aim of investigating the dye decolorization ability of recombinant Pycnoporus sanguineus laccase expressed by Pichia pastoris, we performed the decolorization of three typical synthetic dyes,emazol brilliant blue R(RBBR),reactive black 5(RB5)and indigo carmine(IC),by recombinant laccase using single factor design. Furthermore, we studied the decolorization of mixed dyes composed by these three aforementioned dyes by recombinant laccase. The results indicated that recombinant laccase was weak in dye decolorization without mediation of mediator. Syringaldehyde was the optimum mediator for the recombinant laccase to degrade three synthetic dyes. The optimal pH and temperature for laccasemediator system decolorization were 5.0 and 50 ℃. Under optimal condition, the decolorization efficiency of mixed dyes reached 93%, which demonstrates the potential application of the recombinant laccase in wastewater treatment.