Huyou was used as materials in the study. The function component of flavonoid, a - carotene, P - carotene and other chemical materials benefit for health in Huyou citrus were analyzed. By HPLC method, the content of - carotene, - carotene, hesperidin, naringin and rutin in different citrus were analyzed quantitatively respectively. The flavonoids from different Citrus species and different organs were compared, and further more activity of scavenging hydroxyl free radical in distilled flavonoid ...