The invention relates to application of ring A dioxane flavonolignan in preparing medicaments for resisting hepatitis B viruses (HBV), in particular to application of ring A dioxane coupling type flavone lignan or a pharmaceutically acceptable salt thereof in preparing medicaments for clearing away hepatitis B e antigen (HBeAg), suppressing the HBV DNA replication and treating HBV infection diseases. The flavonolignan has certain activity on resisting the HBeAg, and the intensity of the flavonolignan for clearing away the HBeAg is higher than that of Lamivudine which is a positive control and close to that of 10,000 units / milliliter of alpha-interferon. Meanwhile, the suppression ratio of the compound to the HBV DNA replication is higher than 80 percent in the presence of a concentration of 100 micrograms / milliliter. The pharmacodynamical results indicate that the flavonolignan or the pharmaceutically acceptable salt thereof can be expected to be used for preparing the medicaments for clearing away the HBeAg, suppressing the HBV DNA replication and treating the HBV infection diseases.