Abstract: The low-permeability oil field in complex fault block in the western South China Sea has a large reserve scale, which is a key target area for production capacity replacement in the near future. However, the fault block is characterized by small area, great burial depth of oil reservoir, and complex reservoir characteristics, leading to great challenge in high-efficiency oil field development. In view of the high reservoir heterogeneity, rapid reservoir changes in lateral, and complex main controlling factors for reservoir physical properties, the fine reservoir description technology has been used to accurately predict the distribution of “sweet spot” reservoir, which guides the deployment of development wells; In response to the poor development results by conventional seawater injection due to the strong water sensitivity of low-permeability reservoir, gas injection gravity auxiliary displacement and nanofiltration seawater displacement technology have been researched, and an effective displacement technology series for low-permeability oil fields has been established, improving the injection-production well pattern and enhancing the displacement results; By considering the limited well slot resources on offshore platforms, the technology of high-yield production with few wells has been adopted, and complex well structure has been applied to effectively improve the sweep range of single wells. Meanwhile, supporting technology for the high-efficiency development of low-permeability oil field has been researched and developed, which supports to integrate resources and revitalize internal and surrounding potential, laying a solid technical foundation for production increase of the western oil fields in South China Sea.