This study aimed to optimization of the extraction process of a novel water-soluble millet bran polysaccharide (MBP), and investigated its antioxidant activities in vitro. Finally, the optimal process of ultrasonic-assisted enzymatic extraction of millet bran polysaccharide was obtained as follows: Liquid-solid Ratio of 31:1, enzymatic hydrolysis temperature of 59 ℃, ultrasonic time of 22 min. The extraction amount of millet bran polysaccharide was 3.87%. MBP-1 was extracted from millet bran by ultrasonic-enzyme-assisted method, and DEAE-52 cellulose and Sephadex G-100 were used for isolation and purification. The strong scavenging ability to hydroxyl radical, DPPH, superoxide radical and ABTS radical, and strong Fe2+ chelating activity, and the high inhibition rates of α-glucosidase and α-amylase in vitro indicate that MBP-1 possessed strong antioxidant and hypoglycemic activities. The results shown that MBP-1 can be used as potential hypoglycemic agent and have certain application prospects in food-related fields, such as functional food additives.