Abstract: Based on the previously obtained characterization on the RaDtxR gene of Riemerella anatipestifer, upstream and downstream primers were designed with BamHⅠ and Xho Ⅰ restriction enzyme sites added at the 5'-teriminal. These quence of the RaDtxR gene was amplified and cloned into the prokaryotic expression vector pGEX-4T-1 to generate recombinant plasmids pGEX-4T-1-RaDtxR. Then, the expression conditions were optimized by IPTG induced by SDS-PAGE, and the biological activity identified by Western blot. SDS-PAGE and Western blot confirmed that the protein with a molecular weight approximating 51 ku was well expressed with a significant biological activity. Therefore, the highly efficient expression ofthe RaDtxR protein would provide a basis for further study associated with the specificgene.