Inclusion body hepatitis and hydropericardium syndrome (HHS) associated with fowl adenovirus (FAdV) infections occurred worldwide. In this study, we confirmed an outbreak of HHS in captive peacocks in Henan Province, China. The causative agent fowl adenovirus serotype 4 (FAdV-4) was isolated and designated HN19. Phylogenetic analysis showed that HN19 isolate was clustered in FAdV-C. Animal experiments showed that HN19 exhibited high pathogenicity to chickens. The findings suggested that the possibility risk of cross-host transmission of FAdV-4.