Abstract: Many seagrassassociated and growthpromoting bacteria are able to synthetize phytohormone, facilitate nutrient absorption and help to resist pathogens and they play a vital role in seagrass growth and primary production. In this study, 131 strains in 36 genus and 61 species, dominated mostly by genus Bacillus were isolated from seagrass Thalassia hemperichii and Enhalus acoroide in Xincun Bay, Hainan, using phosphorus or nitrogen limited medium. The diversity analysis indicated that sample from T. hemperichii had higher OTU numbers, Chao and Shannon index thanE. acoroide, suggesting a higher bacterial diversity in contrast to the results from PSM medium which got the lowest diversity among the three media. Moreover, 61 strains including 17 phosphate-solubilizing bacteria and 12 nitrogenfixing bacteria were randomly selected to test the plant growthpromoting traits. The results showed that the nitrogenase activity of strain L-2 reached 14.27 nmol C₂H₄·h^-1·mL^-1, and the dissolving phosphorus content of 3 strains ranged from 29.91 to 44.86 mg/L. Meanwhile, 6 strains had good performance in producing siderophore, 8 strains of selected strains were superior to produce NH₃ and 10 strains’ IAA yields were higher than 50 μg/mL. Based on the analyses, 5 strains are considered as potential seagrass growthpromoting bacteria. The 16S rRNA gene sequencing results showed that 2 strains were Bacillus sp., and the remains were Klebsiellasp., Raoultella sp. and Breoghaniasp., respectively. Thus, these 5 bacteria can be developed as microbial inoculant in the future work and applied to stimulate the growth of transplanted seagrass for the protection and restoration of seagrass ecosystem.