Aiming at the problem that high frequency surge waveform testing method for fault diagnosis of interturn short circuit of motor winding had the disadvantage of being too sensitive and not portable, a portable MCA technology was introduced, which regarded the motor as a complex equivalent circuit including inductance and resistance, applied a high frequency sine wave to motor with ALL-TEST IV Pro motor fault detector, and produced three key parameters: the impedance, the doubling frequency value and the phase angle, so as to realize the quick diagnosis and location of the fault such as interturn short circuit of motor winding and the broken guide bar of the squirrel cage rotor. The test results showed that this method could improve the accuracy of motor fault diagnosis.