Abstract: Taking Trihoderma viride L4C as production strain， the influences of carbon source， nitrogen source， inoculum level， incubation time， cultivation temperature and initial pH value on cellulase activity produced by liquid fermentation were studied in this paper. On the basis of single factor tests， orthogonal test was made to study the optimal liquid fermentation conditions. The results showed that the incubation time had the largest effect on the yield of cellulase. The optimal condition was listed as follows: carbon source was the mixture of straw powder and cellulose powder， nitrogen source was ammonium sulfate， inoculum level was 15%， incubation time was 5 days， cultivation temperature was 28℃， initial pH value was 50. Under this condition， the activities of CMCase and FPAase were 1 31516 U·mL-1 and 1 28277 U·mL-1， respectively.

Key words: Trichoderma viride, liquid fermentation, cellulose, FPAase