Abstract: Batch cellulase production with 15 g/L sulfite pulp in 10 L fermenter by Trichoderma reesei,the filter paper activity,cellobiase activity,cellulase productivity and cellulase yield were 2.15 FPIU/mL,0.20 IU/mL,16.3 FPIU/(L·h) and 143.4 FPIU/g pulp,respectively;Raising substrate concentration from 15 g/L to 27.5 g/L with a fed-batch mode,the filter paper activity,cellobiase activity,cellulase productivity and cellulase yield were 3.90 FPIU/mL,0.35 IU/mL,23.2 FPIU/(L·h) and 141.8 FPIU/g pulp,respectively.In contrast to batch process,fed-batch process can increase cellulase activity and cellulase productivity,retain the cellulase yield,and reduce the cost of cellulase production.