Abstract: Objective To understand the genetic characteristics of hemagglutinin (HA) of Influenza A (H1N1) pdm 09 (H1N1) virus in Dongguan during 2010-2011. Methods The nucleotide sequences of HA gene of (H1N1) viruses were obtained by using RT-PCR and gene sequencing techniques. The characteristics of HA sequences were analyzed with bioinformatics software. Results The length of the nucleotide sequence of HA gene obtained by sequencing was 1701 bp and its corresponding amino acid sequence length was 566aa. During this period the mutations of 24 animo acid sites were found, among them 12 mutation sites were in single virus strain. Only 145,202, 391 and 468 sites had obvious change trend, among them 202 sites was at Sb antigen epitope. The receptor binding locus, potential glycosylation site and disulfide bond were relatively stable, no change occurred. Conclusion The main functional region was conserved, no change was observed. Only four sites in all HA sequences had obvious change trend, 1 located at antigen epitopes, which was the result of the mutation accumulation in antigen drift of influenza virus.