Ginseng polysaccharides were extracted by water decoction from Panax ginseng C. A. Meyer (Cultivated Ginseng), named CGPS. Four polysaccharide fractions, CGPS-20, CGPS-40, CGPS-60 and CGPS-80, were precipitated at final ethanol concentrations of 20%, 40%, 60% and 80%, respectively. Physicochemical properties, molecular weight, monosaccharide composition and antioxidant capacity of polysaccharide fractions were all investigated. The results indicated that changing the concentration of ethanol could precipitate polysaccharides into fractions with different molecular weights, functional group composition and physicochemical properties, eventually leading to differences in antioxidant activity, which would help to find a simple, efficient, and reliable method for rapid extraction and purification of antioxidant polysaccharides from Panax ginseng C. A. Meyer. Among the four polysaccharide fractions, CGPS-80 had lower molecular weight, higher contents of uronic acid and total phenolic, and
stronger scavenging ability on DPPH∙ and ABTS∙+ radicals.