Abstract: Nowadays,it is still unknow whether the avian tembusu virus could infect breed Muscovy duck.For the first time,we obtained a viral isolate(named WYZLJ-1359)from ovary of breed Muscovy duck with decreasing egglaying rate,and confirmed the infectious agent as avian tembusu virus(ATV)using RT-PCR.Resultsof sequence comparison with viral genome showed that the main molecular characteristics of genome sequence of WYZLJ-1359strain were in accordance with those of other viruses isolated from other domestic poultry since 2010,and shared no less than 98.4% nucleotide sequence identity with each other.Phylogenetic analysis showed that all ATVs isolated since 2010shared closed relationship with each other.And the genetic distance(GD)among these viruses were all no more than 1.8%,which was far less than the GD between WYZLJ-1359strain and those viruses reported before2000.These results indicated that although the host spectrum of avian tembusu virus continued to increase,the virus showed genetic stability during the process of spread among different poultry species without deletion or insertion in viral genome.