Abstract: In order to accurately describe the characteristics of the relative permeability curve in the whole water cut stage,a method of determining the relative permeability curve to characterize the high water injection multiple was proposed.It was based on the statistical analysis of a large number of laboratory experimental data involving relative permeability.With this method,researchers analyzed the relative permeability curve and the change rules of high water injection multiple were analyzed,.Then,the method of the conventional relative permeability curve correction to high water injection multiple relative permeability curve was established.This method has been applied in the field and the application results have been analyzed.The results showed that the relative permeability curve of high water injection multiple possesses semi-logarithmic piecewise linear characteristics bounded by a turning point in the water cut stage.Before the turning point,the oil-water relative permeability curve remains constant.After the turning point,the residual oil saturation decreases and the oil-water relative permeability curve extends to its limit according to the water injection sweeping rule.The study showed that the transformation from conventional relative permeability curve into relative permeability curve of high water injection multiple could reasonably extend the change rules of high water injection sweeping stage,and extend the applicable range of the current lab seepage curve.The results could provide a theoretical basis for the development of old oilfields.