NS1 is a non-structural protein of the influenza A virus, which could only be expressed when cells are infected. The effect of NS1 protein on host cell is still not clear. To understand the role of NS1 protein in cell infection, recombinant plasmid pCMV-myc-NS1 was constructed, and then transfected into A549 cells. Two-dimensional electrophoresis was employed to analyze proteins regulated by NS1 that could reflect the interaction between influenza virus and host cells at the protein level. The influence of NS1 on cell proliferation and cell cycle was also studied. The result showed that not only could NS1 remarkably affect metabolism, but it could also slow down cell proliferation through blocking cell cycle.