Abstract:To solve the problem of selecting the drying method of raw materials in the production process of Brassica rapa L. polysaccharide， polysaccharide was prepared by water extraction and alcohol precipitation with ′small ginseng′ Brassica rapa L. from different regions. The effects of hot air drying and vacuum freezedrying on the structure， physicochemical properties， and antioxidant activity of Brassica rapa L. polysaccharides from three different sources were investigated by ultraviolet absorption spectrometry， Fourier infrared spectroscopy， Congo red staining， gas chromatography，and thermochemical analysis. The results showed that the extraction yield （3.47±0.25）% and polysaccharide content （24.20±4.86）% were generally higher under hot air drying. Brassica rapa L. polysaccharide is mainly composed of arabinose， glucose， and galactose. The primary structure of Brassica rapa L. polysaccharide was significantly affected by different drying methods， but the higher structure was less affected. The thermochemical analysis results showed that the thermal stability was stronger under hot air drying. The emulsification property （72.76±0.30） m2/g and emulsion stability（17.72±0.92） min of Brassica rapa L. polysaccharide under vacuum freeze drying were better than those of commercial protein （29.40 m2/g and 14.90 min）. The water vetention （89.75±0.97） g/g and oil retention（45.47±0.78） g/g of Brassica rapa L. polysaccharides under hot air drying was generally better. The scavenging rates of hydroxyl radical and ABTS+ radical of Brassica rapa L. polysaccharide obtained by hot air drying were the highest， with half maximal inhibitory concentration （IC??) of 1.097 mg/mL and 0.467 9 mg/mL. The results indicated that hot air drying was a better way to obtain high-quality Brassica rapa L. polysaccharides.