Legionellosis is the major problem in the world but the treatment of the disease is very difficult. The disease caused gene is Legionella and the bacterium is Legionella pneumophila. Kegg is used for the Legionellosis pathway identification. From the MGDB database list of genes present in the Legionella pneumophila are identified. The target gene for Legionellosis had been identified in NCBI. The expression of the target HtpB is viewed through Jcat. Comparative analysis of the target HtpB were done through Biocyc tool. Structural characterization of HtpB nucleotide and protein were carried out through tools like Protein colour, Yaspin, Ronn….etc. Biophysical Characterization of HtpB Protein were done using Dipole moment server.