We compared the ways of deproteinization for crude polysaccharides of Coprinus comatus, and finally selected Sevage method as the optimal method. Two main fractions of Ccp-I-A and Ccp-I-B were obtained after DEAE-52 cellulose and Sephadex G-200 chromatography, both were white-floc, soluble in water, insoluble in absolute ethyl alcohol acetone and other organic solvents. Additionally, Fehling reagent, CTAB, Sulphuric acid-carbazole, iodine-potassium iodide reaction and ferric trichloride reaction were all negative. GC analysis showed Ccp-I-A was composed of mannitose, glucose and galactose in molar ratios of 2.03:9.52:1, whereas Ccp-I-B was composed of fucose and galactose with molar ratios of 1:5.21. Antioxidant activity test showed that Ccp-I-A and Ccp-I-B had good scavenging abilities on DPPH and ·OH. Compared to Ccp-I-B,the scavenging activity of Ccp-I-A was much stronger (72.1% versus 55.3%) when the concentration was 300 μg/mL.