Objective] The purpose of this study was to evaluate the effects of five variables （steaming time, moisture content before inoculation, inoculation amount, fer-mentation temperature, fermentation time） on the sweetness of sweet oats, obtained the best fermentation conditions. [Method] Plackett-Burman （PB） was to evaluate the effects of five variables, and selected significant factors. The steepest ascent was used to approach the optimal response surface experimental area. The optimal fer-mentation condition was obtained by central composite design and response surface analysis. [Results] It was indicated that moisture content, inoculation amount and fer-mentation temperature had significant influences on the content of the reducing sugars. The optimal conditions of moisture content, inoculation amount and temper-ature were 45.26%, 0.014%（g/g） and 28 ℃, respectively. The predicted value of the reducing sugar content was 13.16 mg/g. [Conclusion] Under the optimal conditions, the content of the reducing sugars in the sweet oats could be up to 12.91 mg/g, which was on the whole consistent with the predictive maximum value.
