The present invention relates to a method for conversion preparation of a riemerella anatipestifer pre-bacterial ghost vaccine by using phage PhiX174 E gene and staphylococcal nuclease A gene, and an application method. According to the technical scheme, the phage PhiX174 E gene and the staphylococcal nuclease A gene are coupled to form the series coupling gene through the flexible coupling arm (Gly4Ser), a temperature control expression vector pBV-E-SN is further constructed, the pBV-E-SN is transformed into riemerella anatipestifer protoplast through electric shock conversion, the positive clones are screened and are subjected to bacterial amplification culture at a temperature of 28 DEG C, the bacteria are separated, a protection agent is added, and sub-packaging and freeze-drying are performed. According to the present invention, the prepared live bacterial vaccine is immunized through drinking water, such that the local immunity on the respiratory tract mucous membrane and the digestive tract mucous membrane can be irritated, and the humoral immunity can be stimulated.