Abstract: In view of problem of spectrum leakage and spectrum analysis difficulty caused by windowing and truncation existed in traditional spectrum analysis theory, a new fault diagnosis method of broken rotor bar of motor based on AR model and LMS adaptive notch was proposed. The method uses LMS adaptive notch to filter out fundamental component of stator current, then conducts spectrum estimation of AR parameter model and accurately detects amplitude and frequency of fault characteristics. The method provides a new way for fault detection of broken rotor bar of motor.