The structure of purified components (f2 and f3) of Corbiculidae polysaccharide (CPS) was studied using periodate oxidation, Smith degradation, gas chromatography (GC), methylation, and GC-mass spectrometry (MS) techniques. The results showed that f2 and f3 had different sugar chain structures. The main chain of f2 was composed of a α-D-(1→3) linked glucose (Glc) and α-D-(1→4) linked Glc, with the branch being composed of α-D-(1→2) linked Glc and α-D-(1→6) linked Glc. The main chain of f3 contained α-D-(1→3) linked Glc and α-D-(1→3) linked galactose, while the branch contained α-D-(1→6) linked Glc. The hepatoprotective activity of CPS was evaluated using a mouse model of carbon tetrachloride (CCl4)-induced liver injury. The results showed that oral administration of CPS significantly reduced the elevated serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and liver malondialdehyde (MDA) level (P < 0.05) and significantly increased the activities of liver superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) (P < 0.05). This suggests that CPS exhibits potent hepatoprotective effects on CCl4-induced liver damage in mice, which may be related to the enhancement of antioxidant capacity and inhibition of lipid peroxidation in mice.