Abstract: The crude guava polyphenols was extracted by the microware assisted extraction, and then purified with NKA-9 macro porous resin. After the separation of purified guava polyphenols with the Sephadex LH-20, four different components were obtained (GP1, GP2, GP3 and GP4) . The total antioxidant activity (T-AOC) , DPPH radical scavenging, hydroxyl radical scavenging and superoxide anion scavenging were selected to study the antioxidant activity in vitro of the crude guava polyphenols (CGP) , the purified guava polyphenols (PGP) and the four different components. Ascorbic acid (VC) was used as the positive control. The results showed that the GP4 had the strongest total antioxidant activity, followed by VC, GP3, GP2, PGP, CGP and GP1. And the guava concentration and free radical scavenging capacity was a linear relationship within a certain concentration range.