The invention discloses a method and a device for testing and evaluating tolerance of a drive motor system of a frequency converter under power supply disturbance. The method comprises steps as follows: 1, an instantaneous voltage disturbance resisting test; 2, a long-time voltage fluctuation test; 3, a harmonic disturbance test. The device comprises a power supply grid, a switch Q1, a switch Q2,a switch Q3, a power supply disturbance generator, a tested frequency converter, a tested electric motor, a pulled power generator, a filter device, a voltage compensator, a storage battery, a measurement control unit, a base, a rotating shaft, a UPS (uninterrupted power supply) and a grid-connected frequency converter. The device has the advantages that the device has accurate voltage regulationand frequency modulation and high fault simulation capability and can realize the functions of energy feedback, coordination control of rotating speeds and torque, high-speed and high-accuracy acquisition of the electric quantity and the mechanical quantity, measurement of temperature rising of a motor winding, control of software and machine starting and stopping, torque control, real-time display, wave recording, switch control as well as data analysis and computation.