Abstract: The solid-state fermentation medium formula mainly composed of corn powder and bran with yeast as fermentation starter was screened and optimized by single factor experiment design method. The inoculation quantity, ratio of material to water, fermentation temperature, fermentation time and other factors were used as the evaluation indicators, and the best fermentation conditions were determined. The results showed that the screened best culture medium formula was as follows 75% of corn powder, 21% of bran, 2% of NH₄NO₃, 1% of KH₂PO₄, 1% of MgSO₄. Furthermore, the optimum fermentation conditions were as follows the inoculation quantity was 12%, the ratio of material to water was 1∶1.5, the fermentation temperature was 30 ℃, and the fermentation duration was 66 h. The highest crude protein content （20.56%） of the final fermentation product was obtained under this condition.

Key words: corn powder, bran, yeast, solid-state fermentation, single cell protein feed