The invention utilizes a microbial fermentation technology to improve the forage nutritional value of the cottonseed meal, so as to improve the forage quality of the cottonseed meal, increase the addition proportion in the forage and realize the promotion of the protein nutritional value and the feeding value of the cottonseed meal, aiming at the disadvantages that cottonseed meal is rich in antinutritional factors of free gossypol, cellulose, oligosaccharide, phytic acid and the like, the protein quality is relatively poor and the content of essential amino acids of methionine and the like is low and unbalanced, so that the large-scale forage of cottonseed meal is restricted. The method for improving forage nutritional value of cottonseed meal through the microbial fermentation adopts the technology of 'composite enzymatic hydrolysis and multi-strain three-step solid-state fermentation', so as to prepare the fermented cottonseed meal product that is high in the free gossypol, cellulose degradation degree and the protein content; the cottonseed meal product is rich in nutritional ingredients of probiotics, vitamins, enzyme, amino acid, short peptide, high-grade protein and the like; the method for improving the forage nutritional value of cottonseed meal through the microbial fermentation has the advantages of prompting growth and development, improving the utilization ratio of the forage, enhancing immunization, improving intestinal micro ecology, preventing diseases and the like. The method for improving forage nutritional value of cottonseed meal through the microbial fermentation adopts the solid-state fermentation; the manufacturing technology is simple; the energy consumption is low; zero environmental pollution is generated; and the investment is small. Therefore, mass production is easy.