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To improve the research and evaluation effect of remaining oil in high water cut oilfields， this paper sorted out the concept and influencing factors of remaining oil， summarized the research methods and applicable conditions of remaining oil from three aspects of microscopic distribution， macroscopic distribution， and quantitative analysis of saturation of remaining oil， and discussed the distribution characteristics of remaining oil in water flooding reservoirs， heavy oil reservoirs， and chemical flooding reservoirs based on literature research. The difficulties and development trends of remaining oil research were further put forward. The results show that the influencing factors of remaining oil mainly include geological structure， sedimentary microfacies， reservoir heterogeneity， well pattern density， well pattern， perfection of injection-production system， and production performance. The remaining oil research methods include experimental analysis， numerical simulation， field testing， etc. The research purposes and applicable conditions of each method are different， and the test results reflect the distribution of remaining oil saturation at different locations and scales. The distribution of remaining oil in high water cut oilfields is highly dispersed and relatively enriched， and the microscopic distribution of remaining oil is in various forms of continuous and discontinuous phases. The development trend of remaining oil research includes but is not limited to five aspects： the construction of super-large physical models， the integration of multi-scale high-resolution imaging systems， the improvement of numerical simulation methods considering the time-varying and discontinuous nonlinear seepage of different displacement media and physical properties， the comprehensive application of multidisciplinary and multi-method field testing， and the wide application of big data artificial intelligence.