Baijiu Fermenting Grains (BFG) is a main intermediate product during Baijiu distillation process. Zhimaxiang Baijiu Fermenting Grains contains high level of protein which could result in high content of higher alcohols in the final product. A Bacillus subtilis producing acid protease was used in solid state fermentation of BFG, which was supplied by Jiangsu Yanghe Distillery Co. Ltd. Effects of fermentation temperature, fermentation time and water content in solid state fermentation were analyzed by single factor test, and BFG peptides production was further enhanced by response surface methodology (RSM). Moreover, the obtained BFG peptides were analyzed to determine its molecular weight, amino acid composition and anti-oxidant activity. Results showed that the optimized fermentation conditions were as follows: fermentation temperature of 30 ℃, fermentation time of 47 h and water content of 1.2 mL/g. In this optimized condition, the highest BFG peptides production reached 7.04 mg/mL, and the molecular weights of over 50% peptides were lower than 2000 Da. Scavenging activities of DPPH and ABTS radical at BFG peptides concentration of 0.4 mg/mL were 85.5% and 66.2%, respectively. Our study established a method of reducing protein content of BFG and producing antioxidant peptide by BFG solid state fermentation, which could be used to lower the higher alcohols content in future.