Abstract: Abstract: Citrus paradisi cv. Changshan Huyou and Fructus aurantii were used as materials， flavonoids contents were determineds by HPLC and antioxidant activitie were evaluated by methods of FRAP and DPPH. Huyou fruits has a higher content of total flavonoids， the contents in five periods of Huyou fruits were 17386， 15006， 13443， 6533 and 7660 mg·g-1; meanwhile， the content of total flavonoids in Fructus aurantii was 8565 mg·g-1. Flavanone glycosides are the main flavonoids in fruits of Fructus aurantii and Huyou， the main flavonoids were naringin and hesperidin， followed by neohesperidin， narirutin， neoericitrin， ericitrin， hexaMF， heptaMF and tangeretin ect. The antioxidant activities of Huyou was significantly higher than that of Fructus aurantii， and the fruits of Huyou on June 11th had the highest antioxidant activities.

Key words:  Citrus paradisi cv. Changshan Huyou, Fructus aurantii, flavonoids contents , antioxidant activities