Abstract:The polysaccharide was extracted from coix seed by water extraction and ethanol precipitation method assisted with ultrasound.The extraction conditions of polysaccharide were optimized by an orthogonal experimental design，and the antioxidant effects of the extracted polysaccharide was also studied.The results showed that the optimum extraction technology was extraction time 2 h，extraction temperature 75 ℃，pH value 5，and solid-liquid ratio 1∶20（g/mL）.Under the condition，the extraction rate of polysaccharide reached 1.56%.The experiment indicated that extracted polysaccharide had a certain scavenging ability to hydroxy radicals，but the effect was weaker than ascorbic acid under the same quality concentrations.