Abstract: Two kinds of extracts, A and B, were obtained from Euryale ferox seed shell (EFS) extracted with ethanol and its 50% aqueous solution, respectively. The constituents and major polyphenols compounds in extracts were determined by HPLC-UV method, and the antioxidative stabilities under different environments were also investigated in present article. The results showed that there are highly content total phenol in extracts of A and B, they are 763.65and 517.04mg/g, respectively. The major polyphenols compounds in extracts were gallic acid (314.0 and 281.4mg/g) , catechins, rutin (54.68 and 44.81mg/g) and little of chlorogenic acid. The analysis results of antioxidative stability indicated that two kinds of EFS extracts were very sensitive to the high pressure sterilization, ultraviolet and alkali, especially to the alkali, the total reducing power and DPPH radical scavenging ability of extracts completely lost. Treated with strong acid, the total reducing power and DPPH radical scavenging ability had not lost but significantly enhanced. So, the extracts from euryale ferox seed shell could be used in acidic food materials.