Abstract: Optimization of the extraction of polysaccharide from Auricularia cornea Ehrenb. for higher polysaccharide yield was carried out using one-factor-at-a-time method and response surface methodology. Solvent-to-solid ratio,ultrasonic power,ultrasonic temperature and ultrasonic time were used as independent variables. FT-IR was used to preliminary characterize the polysaccharide structure. The in vitro antioxidant activity of Auricularia cornea Ehrenb. polysaccharides was investigated by measuring total reducing power and scavenging activities against 1,1-diphenyl-2-trinitrophenylhydrazine(DPPH),iron ion reduction ability(FRAP)and oxygen radical scavenging ability(ORAC). The results showed that the optimum extraction conditions were found to be extraction at 210 W,62 ℃ for 29 min with a solvent-to-solid ratio of 40∶1 (mL/g). Experiments conducted under these conditions gave a polysaccharide yield of 7.43%. Polysaccharides had the characteristic absorption peak of polysaccharide and proved to be β-pyranose. The IC₅₀ against the DPPH free radical of the Auricularia cornea Ehrenb. polysaccharides was 1.445,and the FRAP and ORAC values were 35.14±0.16 mmol Trolox g^-1and 0.627 mg Trolox mg^-1,which had good antioxidant capacity and could be used as natural antioxidants.