Abstract: The purpose of this study was to develop a bivalent inactivated vaccine against duck infectious serositis.Riemerella anatipestifer strain RAf63 (serotype 1) and RAf34 (serotype 2) were used as the vaccine strains.The strains were cultured and inactivated and concentrated respectively, and then mixed.The bivalent inactivated vaccine was made from the mixture.A double dose of inoculation to 6-day old ducklings were used to determine the safety of the vaccine.To determine the immunogenicity of the vaccine, 6-day old ducklings were vaccinated with the vaccine and challenged with the vaccine strains on the 5th, 10 th, 14th, 21 th, 35th, 49 th, 63th, and 70 thd postinoculation, respectively.The results showed that the vaccine was safe and the protection rate was 90% on the 14 th day postinoculation and the vaccine immunity duration was 60 days.The vaccine can be used to prevent duck infectious serositis caused by Riemerella anatipestifer serotype 1and 2.