Objective:To elucidate the genetic characteristics and deduced protein variation of nonstructural protein(NS)gene of the novel influenza virus A/H1N1 in 2009 pandemic.Methods: The sequence of NS gene of A/H1N1 viruses isolated in North America,Europe,and Asia during 1930-2009 were downloaded from NCBI database.MEGA4.0 software and NJ method were used for sequence alignment,protein sequence alignment,and the phylogenetic tree construction.Results: The NS genes of novel influenza virus A/H1N1 in 2009 pandemic were originated from A/swine/H1N1 virus of 2005-2007; they shared a high homology of 97.5％-97.6%.There was an obvious evolutionary relationship between the NS genes of novel A/H1N1 virus and those of the influenza A/swine/H1N1 viruses isolated in North America from 1930 to 2007.No obvious changes were found in the amino acid sites for the antagonistic function of NS1 against the host antiviral capacity among these viruses.Conclusion: The NS gene of novel influenza virus A/H1N1 in 2009 pandemic might evolve from swine A/H1N1 influenza viruses isolated in the United States.The antagonistic function of NS1 against the host antiviral capacity is not changed.