The invention relates to a preparation method of a divalent composite adjuvant inactivated vaccine of Riemerella anatipestifer. The preparation method comprises the steps of strictly screening bacterial strains of the Riemerella anatipestifer, strictly controlling the process of preparing and inactivating bacterial liquid for preparing vaccine, preparing a novel composite adjuvant to be reasonably mixed with the inactivated bacterial liquid for preparing the vaccine, and emulsifying a resultant to obtain the vaccine. The vaccine prepared by the preparation method provided by the invention has high single-time prevention efficiency and obvious immune effect on the Riemerella anatipestifer diseases, so that the repeated use frequency is lowered, and the use cost is lowered. In addition, the preparation method has the advantages of scientific and systematic design, simplicity in equipment, easiness in operation, and stability in effects of obtained products. Moreover, the preparation method of the divalent composite adjuvant inactivated vaccine of the Riemerella anatipestifer has favorable social benefits and economic benefits.