Abstract: Mevalonate Kinase gene (RAMVA) was obtained when virulent genes of Riemerella anatipestifer were screened from DNA library by specific antibody as probes. The DNA fragment named DQ398751 had been record by GenBank. The length of open reading frame of RAMVA was 492 bp and encoding 163 amino acids. In order to express the gene, the digested PCR product of RAMVA was ligated with digested vector pMAL-C2X, and transformed into host bacteria E. coli BL21(DE3). Finally, the gene was successfully expressed in the bacteria by induction of IPTG, the content of the recombinant protein was about 15.6% of the whole bacteria proteins, and the recombinant mevalonate kinase was in a soluble state. Ducklings′ immune tests showed that two weeks post inoculation of the recombinant bacteria E. coli BL21/pMAL-C2X-RAMVA, the protection rate to Riemerella anatipestifer infection was 42.3%.