Polygonum aviculare L. was extracted by methanol and then fractionated systematically with solvents and column chromatographic method in order to isolate ingredients with anti-lipid peroxidation and liver protectective effects. Among these fractions, ethylacetate soluble part(MWE) showed the strongest in the anti-lipid peroxidation. Furthermore, the crude subtraction(MWE 4) with Rf value near 0.42, which is separated from MWE by column chromatography using a solvent system, inhibited the lipid peroxidation of rat liver in vitro. Moreover, MWE 4 decreased GOT, GPT and TBA value compared with control and suggested high protective effects against hepatotoxicity induced by carbon tetrachloride in mice. The active compounds in MWE 4 were assumed to be flavonoid glucosides.