With dried Eleocharis Tuberosa peel as raw materials, polysaccharide in eleocharis tuberosa peel was extracted by ultrasonic-assisted complex enzyme. Influence of ultrasonic power, ultrasonic treatment temperature, ultrasonic treatment time, complex enzymatic constituent, amount of complex enzyme, on extraction of polysaccharide, were studied. The polysaccharide in Eleocharis Tuberosa peel was purified by water dissolution and ethanol precipitation. The structure of polysaccharide was characterized by IR. Antioxidation property of polysaccharide in Eleocharis Tuberosa peel was determined by UV-VIS spectrophotometer. The result showed that the optimal extraction condition of polysaccharide in Eleocharis Tuberosa peel, were ultrasonic power of 280 W, ultrasonic treatment temperature of 60 ℃, ultrasonic treatment time of 30 min, complex enzymatic constituent of 11.5, amount of complex enzyme of 0.5%. Under the optimal technological conditions, the yield of polysaccharide could reach 28.23%. After purification, the purity of polysaccharide in Eleocharis Tuberosa peel could reach 78.2%, and the clearance rate of polysaccharide for hydroxyl radicals could reach 91.25%, which was close to 0.8 mg/mL ascorbic acid of 94.7%. Theoretical basis was provided for further development and utilization of polysaccharide in Eleocharis Tuberosa peel by the research results.