Abstract: Abstract: Blackcurrant (Ribes nigrum L.) is a kind of small berry with many health-beneficial substances, such as organic acids, unsaturated fatty acids, vitamins, polysaccharides, flavonoids, and anthocyanins. Recently, polysaccharide from blackcurrant (BCP) has received considerable attention for their prominent benefits to human health, including immunostimulation, antitumor, antimicrobial, antioxidant, and anti-inflammatory activities. Previous work from our laboratory had isolated BCP which showed apparent antioxidant activities in vitro. However, the polysaccharides' high molecular weight and low solubility in water limit their absorption and utilization in the body. Thus, the degradation of polysaccharides should be carried out to improve the specific and unique properties. Notably, ultrasonic irradiation has been recently viewed as a new technique for the degradation of polysaccharides, mainly due to the fact that the reduction in the molecular weight is simply splitting the most susceptible chemical bonds without causing any major changes in the chemical nature of polysaccharides. At present, there are no reports on preparing degraded BCP with the method of ultrasonic degradation. In this study, the BCP was obtained through water extraction, 40% alcohol precipitation, and purification with D4006 macroporous resin. The BCP was dissolved in water (6 mg/mL) and then was degraded by ultrasonication at 600 W, 25 °C for 30 min. The degraded polysaccharide (BCP I) was obtained through the subsequent separation with Sephadex G-100. Physical and chemical properties, structural characterization and antiglycation activity of BCP I were preliminarily studied. The molecular weight was determined by high performance liquid chromatography, and the monosaccharide composition was determined by gas chromatography. Infrared spectrum, Congo red and electron microscopy were used to characterize the structure of the polysaccharides. The results showed that the purity of BCP I was 83.88%±0.76%, and the weight average molecular weight was 235 955 Da. BCP I was acidic polysaccharide, and consisted of galacturonic acid, rhamnose, arabinose, mannose, dextrose and galactose in a ratio of 2.31 : 1.11 : 3.14 : 0.34 : 0.36 : 1.00. Fourier transform infrared spectrum showed that BCP I had obvious characteristic peaks of polysaccharides, and BCP I was a pyranose form of sugar containing both α-type and β-type glycosidic linkage. Ultraviolet spectrum showed that BCP I did not contain anthocyanins, proteins and nucleic acids. Scanning electron microscope and Congo red test showed that BCP I exhibited sheet structure and had no triple helix structure, and the surface area of BCP I was reduced compared with BCP. The results of antiglycation assay showed that BCP I exhibited significant inhibitory effects on the product formation of 3 stages of glycation reaction, and the inhibitory rate increased with the increase of concentration and time. The maximum inhibitory rates were 49.55%±0.79%, 41.82%±0.72% and 42.01%±0.13%, respectively, which were higher than those of the control aminoguanidine (30.45%±0.13%，26.59%±0.20% and 23.80%±0.49%). Thus, BCP I can be considered as a kind of potential inhibitor of protein glycation. The results can provide a theoretical basis for further study on the structure-activity relationship between structure and hypoglycemic activity of the polysaccharides from blackcurrant.