To obtain the maximize the concentration of reducing sugar, optimum operating conditions for the hydrolysis of cellolose was investigated by using the response surface methodology. The independent variables were enzyme activity, substrate concentration and reaction temperature and reducing sugar concentration and production yield(reducing sugar concentration per amount of enzyme) were dependent variables. Following the 3³-fractional factorial experimental design, 17 experiments were carried out at various conditions, with 5 starpoints and 4 replicates at the center point. The optimum condition for the hydrolysis of cellulose was as follows, enzyme activity; 274 FPU, substrate concentration; 8.9%, and reaction temperature; 51℃. The maximum production of reducing sugar, 47.89 g/L, was ob- tained in this optimum condition.