Full-length eight gene segments of avian influenza virus A/duck/Hubei/W1/2004(H9N2) (Dk/Hub/W1/04) were amplified by RT-PCR and completely sequenced. Phylogenetic analysis revealed that Dk/Hub/W1/04 was derived from A/Duck/HongKong/Y280/97, not displaying direct evolutional relationship with A/Quail/HongKong/G1/97 or Hubei H5N1 viruses. Meanwhile, Dk/Hub/W1/04 was found highly related to recent three chicken isolates. The connecting peptide of HA and the deletion in NA stalk were consistent with three chicken isolates, and the number of potential glycosylation site on the HA and NA also was similar or identical to the three chicken isolates. These findings suggested that Dk/Hub/W1/04 is likely to transmit back to ducks from chickens.