Abstract: In this study, Trichoderma viride, Aspergillus niger, Candida utilis, Penicillium and Longibrach iatum Rifai were used as fungi, 4 factors ( fermentation temperature, time, inoculation amount of mixed bacteria and the time of yeast access) were selected on the basis of single factor experiment.The orthogonal experiments of solid state fermentation were carried out ( the ratio of mixed bacteria was 1∶ 1∶ 1) , the optimum fermentation conditions were determined by measuring the cellulase activity and the degradation rate of crude cellulose.The results showed that with cellulase activity as the index, the highest activity of the enzyme was the combination of Trichoderma viride, Aspergillus niger and Candida utilis, the inoculation amount of mixed bacteria was 5%, fermentation time was 3 days, yeast and mixed bacteria were accessed at the same time, the fermentation temperature was 30 ℃ and the cellulase activity was 85.73 U/m L.Based on the degradation rate of crude cellulose, the highest degradation rate was the combination of Longibrach iatum Rifai, Penicillium and Candida utilis, the inoculation amount of mixed bacteria was 10%, and the degradation rate of cellulose reached 38.89% when the yeast was inoculated on the first day and fermented at 30 ℃ for 4 days.After the solid-state fermentation of mixed bacteria, the nutritional value of crops were improved and can be used as a high-quality feed to feed livestock.This will play a positive role in making full use of renewable resources and improving rural environmental pollution.