Abstract: Optimization the extraction process of polysaccharide by response surface methodology from Brassica rapa L. and its antioxidant activity were investigated by assays of DPPH free radical scavenging ability and reducing power. The optimal extraction conditions with an extraction yield of 23.72%±0.33% for BRP were obtained as follows:extraction temperature 93℃,extraction time 4.3 h,extraction times 3 and ratio of extraction solvent to raw material 75 mL/g. Furthermore,the BRP exhibited relatively higher antioxidant activity in vitro,DPPH free radical scavenging ability and reducing power of BRP were concentration dependent,the EC₅₀ were 8.55 and 2.25 mg/mL,respectively,hence it could be used as a natural antioxidant in functional foods or medicines.