Total DNA was extracted from the top sediment layer (0-10 cm) of MD06-3047 in the Kuroshio and was used as template for polymerase chain reaction (PCR) amplification employing specific primers for bacterial and archaeal 16S rRNA genes. The 16S rDNA libraries were then constructed. Microbial diversity was analyzed by using restriction fragment length polymorphism (RFLP), DNA sequencing and phylogenetic analysis. The results show that there are six phyla in the Bacteria domain: Proteobacteria, Acidbacterium, Planctanycenea, Verrucomicrobia, Candidate division OP8 and Bacteroidetes, and the phylum Proteobacteria is predominant. In the Archaea domain, Crenarchaeota dominates over Euryarchaeota. There are four divisions in the Crenarchaeota kingdom: MCG, C3, Marine Benthic Group A, Marine Group; three divisions in Euryarchaeota kingdom: South Africa Golden mine Euryarchaeota Group、Marine Benthic Group E and MEG, and the Marine Benthic Group E is the dominating group.