Abstract: The methods for calculation of oil?water relative permeability by water?oil displacement experiment are complex, by which the oil?water relative permeability and outlet water saturation are of few discrete data points commonly, and mainly concentrated in the end of the high water saturation. If using Willhite model to match or calculate the curves of oil?water relative permeability and outlet water saturation, the deviations or errors are usually bigger. This paper presents the improved model and makes case studies. The results indicate that it has high matching accuracy and very small errors. The standardized oil?water relative permeability curves are generally concentrated in the middle range of the core experimental curves, basically consistent with the trend of core data changes, worthy of reference and promotion