In order to achieve the fault diagnosis of the broken rotor bar of the squirrel-cage induction motor in real time, the paper designs the fault diagnosis system of the broken rotor based on LabVIEW. The effect of parameters adjusting on many variable step size LMS algorithms for adaptive notch filter was analysed systemically. In the end, this article takes the stator current signal of the squirrel-cage induction motor as the research object, the adaptive notch filter based on the many variable step size LMS algorithms was used in the fault diagnosis of the broken rotor bar of the squirrel cage induction motor. Experiments show that the system can effectively choice variable step size LMS algorithm for the signal of the broken rotor bar. It has faster convergence speed, lower state error, and to eliminate the interference from the power frequency component. It can better accomplish the fault diagnosis of the broken rotor bar of the squirrel-cage induction motor based on the FFT spectrum.