Four different microorganisms,Aspergillun niger,Bacillus licheniformis,yeast and Lactobacillus planetarium were used for mixed fermentation to reduce the crude fiber from corn stalk in order to improve the nutritional value of the corn stalk.The fermentation conditions were optimized by orthogenal experiments.Results showed that under the condition of inoculation amount of multi-strains（each of Aspergillun,Bacillus,yeast and Lactobacillus） was 2×107 CFU,the ratio of corn stalk powder and wheat bran=2:1,temperature at 37℃ for 6 d fermentation,the crude fiber was reduced 26.68%.When Aspergillun nige and Bacillus licheniformis was mixed at first for 72h fermentation and then mixed with yeast and Lactobacillus planetarium,the crude fiber was reduced by 27.95% and the crude protein content increased to 24.67%.