In order to reduce the production cost of γ-aminobutyric acid and make the best of bean dregs,the fermentation conditions for Monascus ZL307 to produce γ-aminobutyric acid with bean dregs as raw material in solid-state fermentation were optimized.Based on the study of single factor tests,we used Plaekett-Burman design to evaluate the influence of six related factors.Rice flour,MgSO4,KH2PO4 were affirmed the important factors in the medium.After identifying three critical factors,the optimal region of γ-aminobutyric acid production was found by steepest ascent approach.Then response surface methodology was also used to develop a mathematical model to identify the optimum concentrations of the key nutrients for higher γ-aminobutyric acid production,and to confirm its experimental validity.The results showed that the optimal fermentation conditions were as follows: bean dregs 12.28g,rice flour 7.72 g,(NH4)2SO4 0.20%,MgSO4 0.23%,KH2PO4 0.37%,CaCl2 0.25%,sodium glutamate 0.45%,initial water content 60%,initial pH 5.5,temperature 32 ℃.Under the optimum conditions,the yield of γ-aminobutyric acid reached 0.417 mg/g,which was 13.4% higher than before.