〔Abstract〕 Objective To systematically predict the structure and function of theompBgene and its encoded protein from the newly discovered R. Japonica Strain Anhui 120 isolated from the blood of clinical patients in China, so as to provide a theoretical basis for the role in pathogenic mechanisms of rickettsia, the development of diagnostic reagents and vaccines of clinical spotted fever. Methods Based on theompBgene and its encoded amino acid sequence of R.Japonica strain Anhui 120, bioinformatics method was used to predict the signal peptide, transmembrane region, hydrophobicity and possible B cell epitopes. Results There were 15 deletions of consecutive bases of the 3 297～3 311 in theompBgene of R.Japonica strain Anhui 120. In addition, the isolate also had 4 base mutations. The number of amino acids encoded by the gene was 1 651, the molecular weight of the protein was 167.69 ku, and there were 20 kinds of amino acids. The amino acid with more content was Gly. The theoretical isoelectric point pI was 5.15, the extinction coefficient was 58 805 or 58 680, the unstable index was 7.15, the fat index was 88.86, the total average hydrophilicity(GRAVY) was 0.06 and it was hydrophobic protein, the Signal peptide(Sec/SPI) Likelihood was 0.567 7 with signal peptide sequence. There was a Pfam region and autotransporter region, which was associated with bacterial adhesion to host and protein transport respectively. The main secondary structure of the protein was random coils, followed by β-sheet and α-helix, accounting for 53.73%, 30.83% and 15.45%, respectively. In the tertiary structure of homologous model protein, the amino acid of 1 308～1 651 formed a barrel-like structure on the surface of the protein, which might have the action of serine protease. The antigenic epitope in the protein molecule was rich, and there were 159 possible epitopes. The highest predicted score(0.94) was the sequence of 1 269～1 284. Conclusion The composition of theompBgene and its encoded protein, the secondary structure, tertiary structure and B cell epitope of R.Japonica strain Anhui 120 were successfully analyzed and predicted, which provides the theoretical support for the development of pathogenic mechanisms, clinical diagnostic reagents, and subunit vaccines of R.Japonica.