Hepatitis B virus (HBV) is a prototype of hepadnavirus, and hepatitis B caused by HBV infection is a serious public health problem. Using the currently available anti?HBV drugs, including nucleotide analogs and interferon?α, it is difficult to achieve a “clinical cure” endpoint. Thus, new anti?HBV drugs and combination therapy strategies are urgently needed, as are appropriate animal models for preclinical evaluations. Woodchuck hepatitis virus (WHV) was first discovered in woodchucks at the Philadelphia Zoo in the United States in 1978, and has been classified as hepadnavirus due to its comparable genomic structure and replication cycle with HBV. Furthermore, the natural history of WHV infection in woodchucks is highly similar to that of HBV infection in humans; therefore the woodchuck model has been used to evaluate HBV DNA vaccines and anti?HBV drugs for decades. In recent years, many cytokines, their receptors, and other immune cell surface markers have been cloned and identified. Additionally, detection method for T cell responses, including lymphocyte proliferation assays and CD107a degranulation assays, have been established and have greatly promoted the woodchuck model for studies of the immune?pathogenesis and immunomodulatory therapy of HBV infection. This review summarizes the immunological features of the WHV?infected woodchuck model and its application for evaluating anti?HBV drugs and immunomodulation therapies.