Selenization modification can improve the biological activity of natural polysaccharides. With Huaishan yam polysaccharide (CYP) as the raw material, selenium-polysaccharide from Huaishan yam (Se-CYP) was prepared by HNO₃-Na₂SeO₃ method. The preparation technology and α-glucosidase activity inhibition of Se-CYP were studied. The results of single factor test and orthogonal test showed that, with the α-glucosidase inhibition rate as the index, the optimal conditions were as follows: mass ratio of CYP to Na₂SeO₃ was 6:4, concentration of nitric acid was 1.4%, reaction time was 10 h, and reaction temperature was 80 ℃. Correlation analysis showed that the α-glucosidase inhibition rate of Se-CYP was highly positively correlated with the selenium content. FTIR results showed that selenium existed in Se-CYP in the form of selenium ester, and its existence form was mainly as
. Different concentrations of SE-CYP all showed strong inhibition on the α-glucosidase activity, and the higher the concentration, the higher the inhibition rate. The α-glucosidase inhibition rate of Se-CYP was higher than that of CYP at the same concentration. These results can provide a theoretical reference for screening and preparing of high activity and safe α-glucosidase inhibitors.