Abstract: Objective: To study the molecular epidemiological characteristics of dengue fever and the genetic diversity of dengue virus (DENV) in Hainan Province in 2023, in order to accumulate experimental evidence for the traceability analysis and early warning prediction of dengue fever. Method: The information on dengue fever cases in Hainan Province in 2023 was collected through the China National System for Disease Control and Prevention (NNDRS). Blood samples were collected from the cases, and real-time fluorescence quantitative RT-PCR was used for nucleic acid testing. Positive samples were used to isolate the virus, and the envelope (E) protein encoding gene was amplified. The nucleotide sequence was determined and compared with representative strain sequences from major global epidemic areas from 2019 to 2023. Result: A total of 363 cases were reported in Hainan Province in 2023, with the first case reported in July. The peak of incidence was reached in September and October, and the epidemic ended in December, showing obvious spatiotemporal clustering characteristics. Ledong County reported the most cases, mainly dominated by DENV-2 infection (99.58%, 238/239). Among the 38 cases in Sanya City, DENV-1 (20/38) and DENV-2 (18/38) were both prevalent, while other areas showed a low-level sporadic state, mainly caused by DENV-1 infection. Genetic evolution analysis showed that DENV-1 belonged to genotype I, and the nucleotide homology between E gene sequences was 98.79%～100%; The DENV-2 belongs to the Cosmopolitan type, and the nucleotide homology between the E gene sequences is 98.99%～100%. It has high homology with the virus gene sequences of the prevalent strains in Southeast Asia such as Laos and those published in Guangdong Province in China in recent years, indicating that the outbreaks of dengue in Hainan Province may have been caused by the introduction of the disease from Southeast Asia or Guangdong Province. Conclusion: In 2023, localized outbreaks of Dengue in Hainan Province were caused by DENV-1 and DENV-2, with the viruses showing high genetic homology to previously reported viral genomes in Southeast Asia and Guangdong Province.