Abstract: To explore the epidemiological understanding of Newcastle disease virus (NDV) in ducks, 10 NDVs isolated from outbreaks in duck flocks in Shandong Province during 2007-2009 were characterized both biologically and genetically. All 10 strains were velogenic strains based on their MDT (50.460.0) and ICPI (1.66-1.78). Ducklings challenged with the strains showed visible clinical symptoms and autopsy changes, and the morbidity and mortality were up to 70%-100% and 20%-70%, respectively. Compared with genotype Ⅰ-Ⅵ NDV, great variation were occurred, especially at 1-30aa, 101-124aa, 479-494aa and 509-516aa of F protein of the 10 isolates, which displayed the same characteristic amino acid substitutions at position 52, 71, 176, 272, 314, 402 and 489 with NDV strains obtained in recent years. Nucleotide analysis revealed that the homology among the 10 isolates was 95.8%-99.9%, and shared 95.7%-99.8% identities with genotype Ⅶ NDV since 2000, but only 83.8%-90.9% identities with LaSota and F48E9. Phylogenetic analysis showed that all the 10 isolates were of the genotype Ⅶd virus and had two RsaⅠ sites at position 973 and 1 249 bp which were characteristic to most strains of goose origin. The results indicated that the strains of genotype Ⅶd NDV had been the major pathogen responsible for the most epizootic ND outbreaks in duck flocks in China, and NDV isolated from ducks was likely originated from that of goose flocks.