Effects of temperature on xylanase and cellulase synthesis by Trichoderma reesei Rut C30 have been investigated.The culture temperature of 25-26 ℃ could stimulate the synthesis of xylanase and cellulase,the highest xylanases activity(156.53 IU/mL) and CMCase activity(0.589 IU/mL) could be obtained after 96 h cultivation.When culture temperature was 35-36 ℃,the highest xylanase activity(113.73 IU/mL) and CMCase activity(0.208 IU/mL) could be obtained after 48 h cultivation.Temperature was regulated as follows:at the earlier stage(24 h),35-36 ℃,at the later stage 25-26 ℃.It was noticed that synthesis of xylanase was favourated and synthesis of cellulase was depressed,and the highest xylanase activity(161.69 IU/mL) and cellulase activity(0.359 IU/mL) could be obtained after 72 h cultivation.Therefore,temperature regulation could increase the ratio of xylanase to cellulase and favourated the selective synthesis of cellulasepoor xylanase.