After collecting the HA gene sequences of 42 strains of avian influenza viruses (AIV) H5N1 isolated from human (Homo sapiens),poultry and wild birds by searching the GenBank of NCBI,we analyzed the transformation of the amino acid residues at key sites and constructed the phylogenetic tree using DNAStar and compared the homology and evolutionary relationship of these HA genes.The results suggest that HA genes of these AIV H5N1 viruses varies persistently at different rates.Within the same area or neighboring areas in China,the nucleotides are more homologous in the same year or between the continuous two years,indicating that some human AIV diseases may have been caused by the H5N1 viruses infection from poultry.And more researches concerning the role of wild birds are needed.