The ultrasound-assisted extraction condition of polysaccharides from Schisandra chinensis(Turcz.)Baill fruits(SCP) was optimized by Response Surface Methodology(RSM).The results showed that the significant factors of SCP extraction were ethanol concentration,ratio of solid to liquid and extraction temperature.The optimal extraction conditions obtained by RSM were as follows: ethanol concentration(X1) 54.7%,solid to liquid ratio(X2) 1∶ 25,extraction temperature(X3) 58℃.The other conditions were ultrasonic power 200W,extraction time 40min and extraction twice.Under the optimal extraction conditions,the relative extraction rate of SCP could reach to 87.12%(n=3).The ultrasound-assisted extraction was better than traditional method.The Antioxidant activities of SCP on ·OH and ·O2-were determined by spectrophotometry.The results showed that SCP had strong antioxidant activities.