The invention discloses a predication method of the complete characteristic curve of a mixed-flow pump turbine. The predication method of the complete characteristic curve of the mixed-flow pump turbine comprises the steps that an internal characteristic analysis theory describing the flow complete characteristics and the moment complete characteristics are corrected through the feature of the actually measured pump turbine complete characteristic curve; statistics of unit parameters of feature operating points of the pump turbine complete characteristic curves of different specific speeds is conducted, the dominant function relationships between the unit parameter of each feature operating point and the optimal operating condition specific speed of the pump turbine and between the unit parameter of each feature operating point and the guide vane relative opening degree are established; and according to the dominant function relationships, the unit parameters of each feature operating point at different guide vane opening degrees are obtained, so that the undermined coefficient of the corrected internal characteristic analysis theory is determined, and a predicted complete characteristic curve of the pump turbine at any specific speed is obtained. The complete characteristic curve predicted by the adoption of the predication method is small in error, in this way, in a runner model simulation test, only a small number of feature working conditioner need to be tested, and the model test process is guided and accelerated.