Ultrasound-assisted extraction, purification, and characterization of antioxidant polysaccharides from Tricholoma matsutake were carried out. On the basis of the results of a single-factor test, three independent and main variables, including extraction time (X1: 130-170 s), ultrasonic power (X2: 340-380 W), and ratio of water to raw material (X3: 45-55 mL/g) were studied by Box-Behnken design. The optimum extraction conditions are as follows: extraction time 160 s, ultrasonic power 365 W, and ratio of water to raw material 53.5 mL/g. Under the optimized conditions, the yield of T. matsutake polysaccharides (TMP) was 7.97±0.31%. The crude TMP was purified by DEAE-cellulose 52 chromatography and Sephadex G-100 chromatography to afford two fractions, TMP-1 and TMP-2. The crude TMP contained 85.76% carbohydrates, 3.57% proteins, and 0.13% uronic acids. The constituent monosaccharides were predominantly glucose, galactose, mannose, xylose, fucose, and glucuronic acid residues.