Antioxidant activity of the flavonoids from pomelo (Citrus grandis (L.) Osbeck) peel obtained by conventional soxhlet extraction (CSE), microwave-assisted extraction (MAE) and supercritical carbon dioxide (SC-CO2) extraction were investigated. For measuring antioxidant activities, different methods have been used corresponding to different levels of antioxidant action. The results indicated that the extraction yields of flavonoids by MAE and SC-CO2 extraction were higher than that by CSE method, whereas flavoniods by SC-CO2 extraction exhibited the strongest antioxidant activities. Our results indicated that SC-CO2 extraction method could effectively reserve the antioxidant ability of pomelo peel flavonoids.