In view of the demand of a motor stimulator for performance test and power assessment，a load simulating system that simulates the motor port characteristics using the power electronic load is proposed to replace traditional drive platform used in motor driver testing.Real-time digital simulation technology is adopted to obtain the port current state，and the power converter is controlled to accurately track the above-mentioned current，making the converter have the same port voltage and current characteristics as the actual motor.Two typical conditions，one no-load starting and the other abrupt application of load，are simulated.Simulation and experiment results show that the motor simulator has the same port characteristics as the actual motor，proving the feasibility and effectiveness of the proposed scheme.