The immunocompetent tandem fragment FB of the foot-and-mouth disease virus(FMDV) genome was inserted into the expression vehicle pBAD/TOP, to yield an identified recombinant plasmid pBAD-FB, which was used to transform the host bacteria TOP10 and, after induction with different concentrations of the inductant arabinose for varied duration, samples of the expression product were subjected to SDS-PAGE and Western blot analysis. Results revealed that using a final concentration of 0.002% arabinose for induction, expression peaked at 4 h, yielding a product approximately 26 ku in size. Software scanning demonstrated that the FB fusion protein expressed accounted for 28.9% of total bacterial protein, could react specifically with FMDV antibody, and occurred both in the form of inclusion bodies and soluble protein. The soluble fraction of the fusion protein was purified with 50% Ni-NTA resin affinity chromatography, and the fusion protein inclusion bodies extracted. After washing both fractions were separately used to prepare oil-emulsion vaccines, with which guinea pigs were immunized subcutaneously. Neutralization test in suckling mice was employed to assess the neutralization index of the guinea pig serum, and foot-and-mouth disease virus was used to challenge the guinea pigs. The result proved that when the purified soluble product and inclusion bodies were used to immunize guinea pigs, they could induce a high titer of neutralizing antibodies, and provide 100% immunoprotection against virus challenge.