Citrus. reticulata Blanco cv. Suavissima friut has long been regarded as a food and medicinal plant. We investigated the antioxidant activity of the ethanol extract of peel and pulp part of fruit growned in Zhejiang Province, PR. China by several in-vitro systems of assay, namely DPPH radical-scavenging activity, ABTS.+ radical-scavenging activity, ferric reducing antioxidant power (FRAP) assay. Total phenolic content was measured by Folin-Ciocalteu reagent. The total flavonoids contents were measured using a modified colorimetric method.The extracts of different samples were found to have different levels of antioxidant activity in the systems tested. Ethanol extracts of the fruit showed stronger antioxidant activities compared with those of the commercial compound (Trolox). The results suggest that Citrus. reticulata Blanco cv. Suavissima friut can be a good source of natural antioxidant.