Tuber sinense from Yunan was used as the research object, and the extraction process for extracting polysaccharides from Tuber sinense was optimized. The monosaccharide compositions and in vitro antioxidant activities of the purified polysaccharides were analyzed. The optimal extraction conditions obtained via optimization by the response surface method were as follows: extraction temperature 75.36 ℃, extraction time 1.02 h and material-liquid ratio 1:31.32 (g/mL). Under these conditions, the experimental yield of polysaccharides was 11.79%, whilst the predictive yield was11.86%. Four new polysaccharide fractions (TSP-1, TSP-2, TSP-3, TSP-4) were separated and purified from the crude polysaccharides from Tuber sinense by using the DEAE-sepharose fast flow column. The compositions of the polysaccharides were analyzed by ion chromatography. The monosaccharide components of TSP-1 included galactosamine hydrochloride, glucose and mannose in a ratio of 2.8:77.1:20; TSP-2 included rhamnose, glucosamine hydrochloride, galactose and mannose in a ratio of 18:1.4:44.7:35.9; TSP-3 was composed of rhamnose, glucosamine hydrochloride, glucose, mannose, glucuronic acid and galactose in a ratio of13:3.5:58.4:21.1:2.7:1.2. In the range of 0.25~4 mg/mL, the maximum rates of crude polysaccharide (crud TSP), TSP-1, TSP-2 and TSP-3 were 73.93%, 36.67%, 73.60% and 54.10% for scavenging DPPH radical, 60.47%, 36.20%, 41.87% and 52.73% for scavenging ABTS radical, 61.63%, 27.00%, 52.50% and 43.17% for chelating metal, and 0.39, 0.34, 0.28, 0.56 for the absorbance corresponding to reducing power. This research aimed to provide a theoretical foundation for the study of the bioactive material basis and the development and utilization of Tuber sinense polysaccharides. The research results are of great significance to the research and development of wellness foods.