Abstract: Marine-derived strains have important application prospects in the remediation and treatment of high-salt sewage. Hydrocarbons are an important part of sewage. Among them, aromatic hydrocarbon compounds with multiple benzene rings are highly toxic to humans and organisms in environment. However, there are relatively few reports on the anaerobic metabolism of polycyclic aromatic hydrocarbons (PAHs). In this study, PAHs (naphthalene, phenanthrene, pyrene, etc.) were used as the only carbon source and energy source, and PAH-degrading bacteria from the Pacific Ocean's deep-sea sediments were studied by anaerobic enrichment. The analysis of enriched flora showed that Halomonas, Thalassospira, Marinobacter, Oceanobacter and Alcanivorax were the main functional groups, and Halomonas was the most important functional group. A high-efficiency hydrocarbon-degradingHalomonas strain was obtained by screening and isolation, and it was identified and namedHalomonas titanicae PA16-9. The 16S rRNA gene similarity between strain PA16-9 and the model strain Halomonas titanicae BH1^T was 99.52%. Searching result of the NCBI database based on 16S rRNA gene sequence alignment shows that H. titanicae widely exists in wastewater, activated sludge, oil fields, wetlands and other organic matter complex areas. It distributes widely and uses a rich variety of substrates. Growth experiments showed that strain PA16-9 could grow under anaerobic conditions with nitrate as the main electron acceptor, using hydrocarbons such as pyrene, benzopyrene and hexadecane as the sole carbon source. The degradation rate of pyrene reached 61.9% and nitrite gradually accumulated to 0.24 mmol/L in 45 days of cultivation. Halomonas is widely present in the anaerobic hydrocarbon degradation enriched flora, which suggesis that Halomonas may play an important role in anaerobic hydrocarbon metabolism and has great potential practical applications.