In order to solve the problem of accurate simulation modeling and equation solving difficulties of asynchronous motor broken bar fault. By using the simulation module of the winding asynchronous motor, establish the simulation model of the simple broken bar fault in the SIMULINK environment. We discuss the motor current fault diagnosis method of broken bars fault by changing the external resistors of motor to simulate broken rotor bars fault in this paper. By of different resistance to ground resistance and different speed conditions the simulation analysis. Study on the variation law of stator current characteristic frequency, especially the influence of frequency conversion system on the test results. Analysis and experimental results show that the model is simple and easy to use, and the simulation results are similar to the results of simulation test, which is suitable for beginners without experimental conditions.