At present，the commonly used evaluation indicators of water flooding development effects are mostly constructed based on the basic production data of the reservoir，and the evaluation process is relatively cumbersome，and it cannot directly characterize the displacement change characteristics of the underground flow field. Therefore，in view of the distribution characteristics of the subsurface flow field in water flooding reservoirs，by extracting the attribute data of the spatial position coordinates of the streamline and the flow rate and saturation distribution of oil and water phases on the streamline，a flow field potential coefficient characterizing the water flooding capacity is constructed. Furthermore，an evaluation method of water flooding development effect based on the instantaneous flow field potential coefficient is proposed. Taking the north Ng3-4 unit in the west area of Gudao Oilfield as an example，the evaluation of the water flooding development effect after the adjustment of the reservoir flow field was conducted. The analysis results show that there is a positive correlation between the instantaneous flow field potential coefficient and the actual cumulative oil production indicators. Compared with the evaluation methods by means of reservoir engineering or numerical simulation calculation，the newly established evaluation method of water flooding development effect only uses the instantaneous flow field potential coefficient to directly characterize the water flooding potential of the underground flow field，which gets rid of the time dependence of the evaluation index calculation，and realizes the rapid and quantitative evaluation of the long-term development effect of water flooding reservoirs. The practical application in the evaluation of large-scale water flooding reservoir development effects is of great significance.