Abstract: The infection of HBV could cause acute and chronic hepatitis B, and it may lead to hepatocirrhosis and liver cancer eventually. As a defend mechanism of organism to resist external infection, the RNA interference (RNAi) has become a powerful tool for us to study its effects on antiviral infection and gene therapy in recent years. In this article we will summarize the mechanisms of RNA interference and the progress on anti-HBV infection studies by RNAi.