The invention relates to the technical field of medicines, and discloses glabrous sarcandra herb acidic polysaccharide quality product SGP-2. The glabrous sarcandra herb acidic polysaccharide is characterized in that the content of polysaccharide is over 90 percent, and the number-average molar mass is 1,000-2,000KDa; monosaccharide comprises glucose, galactose, mannose, arabinose and galacturonic acid; the bond types of glucosidic bond comprise alpha(1->4)galacturonic acid, alpha(1->4) galacturonic acid methyl ester, alpha(1->4) arabinose, alpha(1->4)mannose, beta(1->6) glucose, beta(1->3)galactose, alpha(1->4)glucose, beta (1->4,6)glucose, alpha(1->3,6)galactose, and alpha(1->4,6)galacturonic acid. The invention provides application of the glabrous sarcandra herb acidic polysaccharide quality product SGP-2 in inhibiting alpha-glucosidase activity and application of glabrous sarcandra herb acidic polysaccharide in preparing a medicament for treating diabetes mellitus, and provides application of the glabrous sarcandra herb acidic polysaccharide quality product SGP-2 in preparing anti-tumor medicaments.