The effects of carbon source on xylanase and cellulase production were studied. The extract of steam-exploded corn stover was found to be the best raw material for producing cellulase-free xylanase. The xylanolytic enzymes of Aspergillus niger An-76 were purified by chromatography, and the properties of the four purified components were analyzed. When the enzyme was used to treat the birch Kraft pulp, and followed by a subsequent CEH bleaching, a brightness of 6.8% SBD more than that of the untreated one using the same chlorine dosage, or a saving of nearly 50% of chlorine consumption with the same brightness, was realized.