Abstract: Reed pulp was pretreated with modified xylanase, and the potential application of modified xylanase in reed pulp biobleaching was evaluated. The results indicated that modified xylanase could reduce chlorine dosage in C-stage up to 60%.The optimum pretreatment conditions of reed pulp with modified xylanase were as follows: pH 7.0, temperature 60 ℃, pulp consistency 5%, enzyme dosage 12 μmol/(min·g)and time 60 min. When chlorine consumption in stage C was reduced by 40% during bleaching, the brightness of bleached pulps from the xylanase pretreated reed pulp reached to 84.0%(ISO),which increased 3.7%(ISO)than that of the control. The enzymatic pretreatment with modified xylanase also improved properties of bleached pulp.