Abstract: The Riemerella anatipestifer (RA)Serotype 2 treated with ultrasonic cracking was used as coated antigen, horseradish peroxidase-labelled rabbit-anti-duck IgG was taken as the second antibody, Tetramethyl Benzidine di hydrochloride (TMB) was used as coloring agent in this test.The indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibody against RA Serotype 2.This method was proved to be very specific, sensitive and repetitive.The result showed that the ducks treated with inactivated vaccine of RA Serotype 2 had specific antibody in their sera detected with indirect ELISA on the 7th day after vaccination.The titre of the antibody was up to peak on the 28th day after vaccination, and then declines, the titre of the antibody on the 56th day after vaccination was higher than that on the 14th day after vaccination.