The change of virulence factors， nutritional components and microbes in cottonseed meal was researched in the bagging solid-state fermentation system with probiotics and proteinase as main participants. The results showed that compared to the unfermented cottonseed meal， the freegossypol decreased by 30.3%， the acid soluble protein increased by 77.8%， and the crude protein was not different significantly in 72 h. In 60 d detection， pH decreased to 5.5 or so， the content of bacillus subtilis was more than 1.0×107cfu/g and mould content was less than 1.0×104cfu/g. Therefore， the application of bag fermentation for producing cottonseed protein， not only improves the nutrition， but also is conducive to the preservation of wet feed.