Abstract: Sequence analysis was conducted on genes of omp31 from 3 different Brucella strain isolated from Inner Mongolia. A pair of primers were designed for amplification of Brucella omp31 genes according to the reported of Brucella omp31 genes complete sequence. omp31 genes were amplified from 3 different Brucella strains by polymerase chain reaction （PCR）, and the PCR products were cloned into pMDI9-T vector and sequences were analyzed. The results showed nucleotide sequences in homology among 3 different Brucella isolates omp31 genes were 100.0 %. Nucleotide sequence in homology was 100.0 % between the three isolates genes and Brucella suis 1330, Brucella ceti B14/94 and Brucella neotomae 5K33, its homology was 99.0 % compared with omp31 gene of Brucella canis RM6/ 66, Brucella melitensis 183 and Brucella melitensis 16M, but the homology between the obtained and Brucella ovis ATCC25840 was the lowest, only 98.8 %.