Abstract: Polysaccharide CRp-1 was extracted from Chionanthus retusus Lindl.et Paxt. seed by water extraction and alcohol precipitation,protein was removed by Sevage method,and purified by DEAE-52 fiber and Sephadex G-100gel column chromatographys. The physicochemical properties,such as total sugar and protein contents,monosaccharide composition,functional group characteristics,spatial conformation were studied by chemical and instrumental analysis,and the inhibitory activity of CRp-1 on α-glucosidase was studied in vitro. The results showed that the polysaccharide CRp-1 that isolated from C. retusus seed was white powder,soluble in water and insoluble in organic solvents,the total sugar and protein contents were 97.12% and 1.65%. CRp-1 did not contain monosaccharides and polyphenols,and also not belong to starch polysaccharides. CRp-1 was mainly composed of rhamnose,arabinose,xylose,mannose,glucose and galactose,with a molar ratio of 1:5.381,1.146,10.804:6.953:11.908,and the molecular weight was 223200 g/mol. UV and IR spectra showed that there were characteristic absorption of polysaccharides and contained furanoside. CRp-1 had a triple helix structure,and the surface was a three-dimensional porous structure,with some round particles. The experiment of α-glucosidase inhibitory activity in vitro showed that CRp-1 had certain α-glucosidase inhibitory activity in a concentration-dependent manner.