<p>In order to conduct in-depth research on fractured carbonate reservoirs and effectively promote the improvement of oil recovery efficiency, this study aims to improve oil recovery efficiency through filtration and nitrogen flooding in fractured carbonate reservoirs. An oil field is selected as the research object to carry out the research, elaborate its geological characteristics, establish fracture standards, and analyze the regional fracture analysis. The parameters of physical large-scale model are designed and prepared, and the fractured carbonate reservoir model is constructed. The core seepage experiment was designed and the seepage results of rock samples were analyzed. Design the water injection nitrogen displacement process, and complete the application test. The test results show that: in fractured carbonate reservoir, oil well location and fracture distribution have a significant impact on oil production effect. When waterflooding oil production, the oil wells far away from fractures perform better; However, due to the characteristics of nitrogen and the existence of fractures, the oil production time of nitrogen flooding is significantly different, and the oil wells near the fractures produce oil quickly at the initial stage, but the overall effect is limited.</p>