Abstract: The phenolic composition of soluble ester-bound and glycoside-bound phenolics from S. gracilis seeds was analyzed by HPLC-MS. The antioxidant activity of phenolic extracts from S. gracilis seeds was evaluated by DPPH radical scavenging capacity,FRAP,TEAC,inhibitory effects on hydroxyl radical induced2-deoxy-D-ribose degradation and DNA damage protective effect. Results showed that the predominant phenolic compounds were caffeic acid,luteolin-glucoside,and catechin glucoside in soluble ester-bound phenolics. And the major phenolic compound was catechin glucoside in soluble glycoside-bound phenolics.The DPPH radical scavenging capacity,FRAP and TEAC of soluble ester-bound phenolics were lower than those of soluble glycoside- bound phenolics. Conversely, the inhibitory effect on hydroxyl radical induced2-deoxy-D-ribose degradation of soluble ester-bound phenolics was higher than that of soluble glycosidebound phenolics. Significant DNA damage protective effects were observed of soluble ester- bound and glycoside- bound phenolic extracts from S. gracilis seeds, and significant correlation( p < 0. 05) was found between phenolic content of soluble ester-bound phenolics and protective effects.