The invention provides a detection system and a detection method of a PG motor. The detection system comprises an input processing module, an amplitude measurement module, a frequency test module, a resistance measurement module, a power measurement module, a communication module, a display module and a master control module. The input processing module is used for amplifying and shaping an input PG signal. The amplitude measurement module is used for measuring the peak voltage and the valley voltage of the PG signal. The frequency test module is used for converting the PG signal into an undershoot. The resistance measurement module is used for measuring the winding resistance of the PG motor. The power measurement module is used for measuring power of the PG motor. The master control module is used for calculating the amplitude of the PG signal according to the peak voltage and the valley voltage, calculating the frequency of the PG signal according to the undershoot, and displaying the amplitude, the frequency, the resistance and the power to a user. The invention can automatically test multiple parameters of the frequency, the power and the amplitude and the like of the PG motor, and improves the fault detection rate of the PG motor test.