Abstract: The immunological activity of the outer membrane protein H (Omp H) of Pasteurella multocida (Pm) was identified. Based on the published data on P. multocida strain X-73 (U50907.1), two pairs of primers were used to amplify the Omp H of P. multocida strain CVCC 44801 by PCR.The amplified fragment was determined to be 1 348 bp (ORF at 1 056 bp). The sequence alignment on Omp H of Pm70, C44-1, P52, XJ121, X-73 and P-1059 with those registered in GenBank showed a nucleotide homology between 80.2% and 98.4% and an amino acid homology between 79.6% and 98.5%. The recombinant plasmid pET-Omp H was constructed and transformed into BL21. The expressed protein was about 56 ku, which was close to the expected molecular weight. The western blot also confirmed its immunological activity. The results would provide the information for the establishment of a viable serological detection method and an applicable Omp vaccine against P. multocida.