During the cooking of the pulp, the xylan partially dissolves, denatures, and deposits again on the fiber surface, thus clogging the pulp matrix. Xylanase is a specific enzyme that breaks down xylan. It only breaks down xylan and cannot break down cellulose. If xylanase is used in this process, part of the deposited xylan can be removed. This not only enlarges the pores of the pulp matrix, releasing trapped soluble lignin, but also allows the chemical bleach to penetrate the pulp more effectively. In this way, the bleaching rate of the pulp can be increased, the amount of chemical bleach can be reduced and the pollution of nature during paper production can be reduced.