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Mature-green tomato fruit (Solanum lycopersicum cv.Zhenfen 202) were exposed to different UV-C irradiation at 2,4,8,and 16 kJ m-2 and then stored under the dark at 14 ℃ and 95％ relative humidity (RH) for 35 d.Of these four doses,UV-C irradiation at 4 and 8 kJ m-2 significantly increased total phenolic contents in present tomato fruit by 21.2 and 20.2％,respectively.Furthermore,UV-C irradiation at 4 or 8 kJ m-2 promoted the accumulation of total flavonoids and increased the antioxidant activity.2 or 16 kJ m-2 UV-C irradiation also enhanced antioxidant activity,but to a lesser extent.Seven phenolic compounds,viz.,gallic acid,(+)-catechin,chlorogenic acid,cafferic acid,syringic acid,p-coumaric acid,and quercetin in tomato fruit were identified and quantified by HPLC.Gallic acid was the major phenolic compound in tomato fruit and significantly correlated with antioxidant activity.4 or 8 kJ m-2 UV-C irradiation significantly increased the contents of gallic acid,chlorogenic acid,syringic acid,p-coumaric acid,and quercetin.The optimum dose of UV-C irradiation in terms of increased phenolic compound content and enhanced Antioxidant activity was determined to be 4 or 8 kJ m-2.