Abstract: With oat as raw material, fermented oats product was prepared by germination treatment and microbe inoculation, the content changes of beta glucan, free amino acids, polyphenols and flavonoids in fermentation process were studied to explore the inhibitory effect and type of fermented oat on α-amylase, and investigate the correlation between the nutrients in the fermented oat and alpha amylase inhibitory effect. The results showed that the contents of β-glucan, free amino acids, total phenols and total flavonoids in oat Jiaosu had an increasing trend with the prolongation of fermentation time, and reached the highest level at 96 h of fermentation. Oat Jiaosu showed inhibition effect on α-amylase, and the highest inhibition rate reached up to 72.27%, with an IC50value of 30.96 g/L; Kinetic analysis indicated that the inhibition of α-amylase by oat Jiaosu at both high and low concentrations belonged to the mixed type. The correlation analysis illustrated that there was a significant positive correlation between the contents of polyphenols and flavonoids in oat Jiaosu and the inhibitory activity of α-amylase（P ＜0.05）, the positive correlation between β-glucan and free amino acid contents and α-amylase inhibition was not obvious. Oat Jiaosu is a promising product with rich nutrients and good nutritive and antioxidative properties.