Aim: To study the antiviral effect of Oenanthejavanica flavones (OjF) on human hepatoma HepG2.2.15 culture system and duck hepatitis B virus (DHBV) infection.Methods: (1) After incubation for 24 h, the 2.2.15 cells were treated with different concentrations of OjF for 12 d. The cell alteration was observed by microscope.The presence of HBsAg and HBeAg were measured using the enzyme immunoas say kit after 2.2.15 cells were treated with OjF for 9 d. (2) Ducklings infected with DHBV intravenously were divided into 5 groups and treated with OjF, acyclovir (ACV), and normal saline respectively for 10 d. All the ducklings were bled before,during, and after treatments at different times, and serum levels of DHBV-DNA were detected by a dot-blot hybridization assay. Results: (1) The 50% toxic concentration (TC50) of OjF was 2.28 g/L. The maximum nontoxic concentration (TC0) was 1.00 g/L. In nontoxic concentrations, OjF significantly inhibited HBsAg and HBeAg in 2.2.15 cells after 9 d of treatment (P＜0.05, P＜0.01). (2) The DHBVDNA levels decreased significantly after the treatment with 0.50 and 1.00 g/kg of OjF (P＜0.01). The inhibition of the peak of viremia was maximum at a dose of 1.00g/kg and reached 54.3% on d 5 and 64.5% on d 10, respectively. Conclusion: The results demonstrate that OjF is a strong inhibitor of HBsAg and HBeAg secretion in 2.2.15 cells and DHBV-DNA levels in the HBV-infected duck model.Acknowledgement The authors wish to thank Zhuang LI for his excellent technical support in this study. This research was supported by Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences.