A predistortortion linearizer, the method that IMD signals are combined at the input port of the amplifier, because of its small size and good efficiency is frequently used in High Power Amplifier linearizer system. The amount of IMD signal cancellation by adjusting the amplitude and phase of predistorter is investigated by new experiment method. In the combining method of predistorter type, the magnitude and phase of combining signals cannot be easily expected due to different magnitude and phase of incoming signals. By experiment, it is measured that a predistortion linearizer has lower amounts of IMD signal cancellation than those of the parallel cancellation method at the same condition (amplitude and phase).