The invention discloses a servo motor type dynamic torque generating system and method, connecting driving motor and load motor with the two ends of a connection shaft, respectively, using host machine system to input rotating speed and torque signal into system controller and input waveform parameter settings into waveform generator, respectively, inputting driving motor and load motor control signals by the system controller and waveform generator to generate dynamic torque signals, using the driving motor to simulate alternating torque signal of shafting drive end, and using the load motor to simulate reverse torque signal of shafting load end, and loading adjustable frequency and amplitude single or multiple harmonic torque signals onto both the drive and load ends, and the phases of the drive and load ends can be different, thus loading rich dynamic torque signals on the tested shafting. And the invention can be used to test actual dynamic characters of various torque sensors.