Corn stover pretrcated with dilute sulfuric acid was hydrolyzcd with ccllulase produced by Trichoderma reesei Rut C-30 on the same substrate. The hydrolysis was described as a summation of three pseudo-first-order reactions and was dependent on ccllulase concentration. A mathematical equation was derived to express the relationship among hydrolysis yield, enzyme concentration, and polysaccharidc fractions with varied extent of hydrolysability.The parameters in the equation were computed with nonlinear regression analysis, and the applications of the equation were discussed.