Abstract: This study addressed problem that the conventional evaluation method of water flooding effect was not suitable for late-stage production in reservoirs with ultra-high water cut, a new evaluation system was studied by selecting indices, determining index weight and establishing an index standard. Firstly, with logical analysis, oil field statistics, and other methods, the team selected 12 suitable indicators for the late-stage high water-cut production from the commonly-used water flooding evaluation indicators. Secondly, standards for various indicators were formulated by integrating “Oilfield Development Level Classification” (SY/T 6219—1996) and oil field statistics. The weight of each indicator was determined by applying an analytic hierarchy process. Finally, the fuzzy comprehensive evaluation method was used for evaluation. In this way, a water flooding effect evaluation method was established for oil reservoirs in the late-stage period of ultra-high water cut. Relevant analogs verified that this evaluation method was relatively accurate, simple and a valuable field practice compared with traditional methods.