Abstract: To detect the diversity and geographical distribution of Thalassolituus bacteria, surface seawater was collected from western Pacific Ocean and Xiamen coastal sea, and enriched with crude oil or directly spread on agar plate. Then, the identified with 16S rRNA gene and subjected to phylogenetic analysis, together with all the sequences retrieved GenBank database. As a result, 32 bacterial strains were isolated in this study，including two belonging to Thalassolituus, while Pseudomonas and Marinobacter were the most dominant oildegrading bacteria, and followed by Alcanivorax and Vibrio. These two Thalassolituusstrains showed 96.9% and 97.0% sequence similarities with type strain T. marinus IMCC1826^T in 16S rRNA gene, indicating that they were potential novel species within genus Thalassolituus. In addition, one Thalassolituus strain was isolated from Xiamen coastal seawater on the ONR7a plate supplemented with crude oil. The phylogenetic analysis showed that all Thalassolituus 16S rRNA gene sequences could be clustered into three distinct groups, i.e. T. oleivorans, T. marinus，and one independent group. They exhibited obvious biogeographic distribution in that bacteria clustered in the same group were associated with the areas they were from, especially the latitude. Temperature is suggested to have played an important role in their distribution. This report for the first time describes the species diversity and geographic distribution of Thalassolituus species in various marine environments.