Abstract: The enzymological characteristics of crude xylanase produced by Trichoderma strain 183 with high xylanase productivity were studied with the following results:cultured on the medium with wheat bran and xylan as the main carbon resource,under 28℃ and 190r/min shaking,the pH and enzyme activity of the broth kept increasing with the growth of strain 183,the enzyme activity reached its peak at hour 84 after inoculation,up to 298.47U/mL.The enzyme has optinal reactive conditions of 50℃ and pH 6,though the enzyme is relatively stable under 40℃ and pH 5～7.Fe2+ and Hg2+ strongly inhibited the activity of this enzyme,while Zn2+,Ca2+ and Cu2+ evidently promoted the activity.