Legionnaires’ diseases (LD) is a bacterial infectious disease which is transmitted into the respiratory tracts through aerosol droplet generated in a water system contaminated with Legionella. Legionella is known to more than 60 sub-species and the most representative strain is Legionella pneumophila. LD occurred 210 cases during the last 3 years in Korea, but there are few studies on the characteristics of Korea isolates. To identify the genetic characteristics of Korea isolates, two strains from clinical (KP14) and environmental isolates (KJ08261) were selected from the 100 Korea isolates by phylogenetic studies, and the analyzed by whole genome sequencing. Biological characteristics including growth kinetics, host cell invasions, and intracellular survival, were compared with reference strain (Philadelphia-1). As a results, the genome size of the two isolates was analyzed to 3,559,584 bp and 3,698,611 bp, respectively, which were larger than those of reference strain (3,397,754 bp). The number of ORFs for two isolates and reference strain was 3,320, 3,178, and 3,003, respectively. The similarity of total genome between three L. pneumophila strains is 96%, which is somewhat lower than the similarity of 97% between the clinical and environmental isolates. Common 2,677 genes were shared in all three strains, and the number of specific genes were 117, 233, and 390, respectively. Growth rates in BYE broth were not significantly different from the three strains, but the infectivity and survival abilities in macrophage cells were observed to be the best in the environmental isolate. This study provided the differential genetic and biological data between the clinical and environmental isolates in Korea and our results will be useful as a basic data for the further study of LD in Korea. This research was supported by a fund (2018-NI001) by Research of Korea Centers for Disease Control and Prevention.