Abstract: A cellulose-decomposing strain CE1 with high enzyme activity was isolated from aging flue-cured tobacco leaves by selection medium and classified as Trichoderma viride.The optimum pH value of the fermentation of CE1 was 6.5,the optimum temperature was 28 ℃,the carbomethyl cellulase(CMC ase) got the highest activity at the 5th day of culture.Crude enzyme of CE1 was used directly for tobacco processing,the results showed that the degradation rate and total sugar of tobacco increased by increasing the concentration of the enzyme.