Abstract: Straw powder was used as the raw material, the solid fermentation conditions of cellulases production by mixed strains of White-rot fungi NS75 and Aspergillus niger NS83 had been investigated. The results of comparative experiments between single strain solid-state fermentation and mixed strains solid-state fermentation showed that, the cellulose enzyme activity produced by mixed strains had increased obviously than that produced in single strain solid-state fermentation, in which, the β-G enzyme activity had increased 120.9% than that produced by White-rot fungi NS75 single fermentation, and the CMC enzyme activity had increased 140.8% than that produce by Aspergillus niger NS83 single fermentation. According to the single factor and orthogonal experiment results the optimum fermentation conditions were determined as follows:ratio between straw powder and bran powder 9∶1, feed-water ratio 1∶2, inoculation volume ratio of White-rot fungi NS75 and Aspergillus niger NS83 1∶1 (v∶v) , start stirring on the third day and once a day, 30℃ culture 5d. Under this conditions, the enzyme activity of CMC enzyme, β-G enzyme, FPA enzyme produced had reached respectively 16650, 16108 and 3164U/g.