11 strains of H9N2 Avian influenza virus (AIV) were isolated from the central region of China from 2010 to 2012,amplifying HA gene with RT-PCR and analyzing the sequence.The purpose of the study was to explore epidemiological characteristics of H9N2 AIV from the central region in the molecular level and provide the basis for comprehensive prevention and control of the disease.The results showed that 11 strains of H9N2 AIV are typical low pathogenic strain.HA nucleotide and amino acid homology of 11 isolates was 89.5~99.9%and 91.6-99.8%,respectively.The 11 isolates were all belong to the Eurasian lineage.there was one more glycosylation site NGT in 145-147aa of 3# to 8# strains.From the evolutionary level,3#-8# strain and swine and wild bird influenza virus (SW/SD/1/03,Bird/GX/62/05) evolved from 9# strain (A/Chicken/Shangdong/SD/2011) ,which were related to Hongkong isolates of G97 and Y280 strains and belonged to the same branch.1#,2#,10# and 11# strains had close evolutionary relationship with three human influenza virus (environment/Hunan/1-70/07,feces/Hunan/2-28/07,feces/Hunan/3-91/07) .Similarly,there was also one more glycosylation site NCS in the 313-315aa of HA.10#,11# and three human influenza virus evolved from 1# and 2# strain.The result demonstrated that there were polymorphism variation trends of H9N2 AIV in ecology.The phenomenon of mutual transmission and evolution existed in different host animal (Swine,wild bird and human) ,and this trend have been strengthened.The above result suggested that real-time monitoring was used for the dissemination and evolution of H9N2 AIV,providing the basic data for the effective prevention of human and animal influenza.