NS1 protein is the only non-structural protein of influenza A virus,which is encoded by the collinear mRNA transcribed from the viral RNA segment 8. It is a RNA-banding protein which has important posttranscriptional regulatory activity. It accumulates in the nucleus of the infected cell at early times but is also present in the cytoplasm later in the infection, Two functional domains have been identified in the NS1protein: a RNA-binding domain at the N-terminus, and an effector domain at the C-terminus, which are associated with the inhibiting host celluar protein synthesis, inducing apoptosis and resisting the production of interferon-α/β. In addition, NS1protein could provide a means for the distinction between vaccinated and virus-infected poultry and act as a vaccine vector because it can tolerate large inserts of foreign sequences. Moreover, it might be an attractive target for antiviral drug design. All of these demonstrate that NS1 protein have the potential application benefits.