Fermentation conditions were optimized by taking Carboxymethyl cellulase enzyme (CMCase) activity as a response indicator for cellulase production from Trichoderma koningii using response surface method (RSM). Three factors that affecting CMCase activity were screened out among pretreatment methods of raw material, nitrogen sources, initial pH values, amount of inoculation, days of fermentation and volume of liquid, they were days of fermentation, initial pH values, and volume of liquid. The optimum conditions of fermentation and their interaction of the three factors were determined through Box-Behnken design and regression analysis using design expert software. The results showed that the CMCase activity could reach 179.15 U/mL, increased by 24.52% under the following conditions: pretreatment methods of raw material was alkaline treatment, nitrogen source was 0.2% (NH4)2SO4, initial pH value was 5.8, inoculation dosage was 5%, volume of liquid was 22 mL, and day of fermentation was 5 d.