Abstract: To improve accuracy of transient process dynamic simulation for pump-storage power plant, in this work we studied advantages and disadvantages of the Suter transformation and its modifications, analyzed in depth the interconnection between unit flows, and introduced a new independent variable of relative opening. Then, an optimized form of this transformation was derived by adopting coefficients of constant correction according to the variation trend of the curves. This leads to our development of a new method for processing pump turbine characteristic curve. Application of this method to an engineering calculation shows an agreement of the results with the experimental data as well as its applicability and efficiency.