Abstract: In order to prepare the polyclonal antibody of Fusobacterium necrophrum,so as to promote the research of genetic engineering vaccine from Fusobacterium necrophrum,the study used A25 gene DNA as template to amplify four fragments of 43 K OMP gene overlap each other, and constructed prokaryotic expression vector.The purified protein was immunized to rabbits by prokaryotic expression system of E.coli,and then the polyclonal antibody was prepared and identified.The results showed that the truncated 43 K OMP proteins were successfully expressed, and the length of the truncated protein size was 32 kDa, 30 kDa, 28 kDa and 30 kDa respectively.The polyclonal antibodies 43 K OMP-1,43 K OMP-2,43 K OMP-3 and 43 K OMP-4 prepared by the protein were 1∶25 600,1∶51 200,1∶25 600,1∶51 200.The prepared antibody can recognize natural 43 K OMP,which lays a foundation for the research of genetic engineering vaccine of Fusobacterium necrophrum.