The objective of this study was to determine flavonoids and their antioxidant capacities in Chinese Jujube. After initial separation by macro-pore resin, extracts of 60% ethanol were further separated by silica gel column and fractionation FJ-1 was obtained. The composition and structure of this fractionation was analyzed by HPLC, IR and HPLC-MS. The ability to eliminate O2• and •OH of this component was analyzed. Content of total flavonoids in Chinese Jujube was 97.98%. FJ-1 was initially determined to be flavonol with molecular weight of 352. When 0.4mg/mL flavonoids was added, 94.6% of •OH and 73.33% of O2• can be eliminated respectively. FJ-1 shows excellent antioxidant capacity and has dose-effect relationship.