Abstract: Enzyme-assisted organic solvent was used to extract the pigment from eight kinds of seaweeds such as brown algae,green algae,red algae and microalgae. A seaweed with highly antioxidant activity was selected by measuring pigment content and antioxidant activity by studying the effects of different processing methods on its antioxidant activity. The correlation between pigment content and antioxidant activity was analyzed.The results showed that the crude extracts of eight kinds seaweed on pigments had certain antioxidant activity in vitro. The antioxidant activity of Laminaria japonica,Undaria pinnatrfida(Harv.)Suringar and Ulva pertusa were better,especially in Laminaria japonica. At the final concentration of 0.8 mg/mL,its scavenging rate of DPPH radical,hydroxyl radical and the superoxide anion radical were 52.58%,68.14% and 60.79%,respectively. The pigment content and antioxidant activity of three kinds of Laminaria japonica were:fresh Laminaria japonica > salted Laminaria japonica > dried Laminaria japonica. Correlation and linear regression showed that the correlation between the three free radical scavenging rates and the content of chlorophyll and carotenoid were both up to 0.75,and there was significant correlation between them. The effects of chlorophyll content and carotenoid content on the three free radical scavenging rates was synergistic,but the relation between carotenoid content was more correlated with the three free radical scavenging rates.