Abstract: Lignin peroxidase(Lip) was produced by Phanerochaete chrysosporium fermentation and the fermentation broth was used to degrade azo dye,Carplon red.The initial reaction rates of dye degradation by Lip were experimentally measured by on-line analysis with HP8452A UV/Vis spectrometer at different concentrations of H ₂O ₂ and Carplon red.The experimental results showed that the initial reaction rates were inhibited by high concentration Carplon red.A mathmatical model considering both two-substrate reaction and substrate (dye) inhibition was proposed and a reaction rate equation was derived.The model simulations were in good agreement with the experimental data.In batch degradation process,automatic disappearance of H ₂O ₂ and Lip deactivation by H ₂O ₂ were observed,and the cation free radical of dye was converted into degradation products.Based on the above experimental results,a model was established to describe the Lip-catalyzed batch dye-degrading process.The results indicated that the model was able to simulate the experimental data,and the average deviation is less than 10%.