The induction motors are widely used in different industry areas which can experience various kinds of faults in stators and rotors. In order to early diagnose motor faults, the classical condition monitoring method focusing on stator current spectrum is well researched and presented. There are already some review papers related to traditional current monitoring method. However, when it comes to the stray flux detection, almost no researchers did a general review on this topic. This paper mainly presents the review of stray flux detection of induction machine. The development and application of stray flux detection method are detailed presented. Comparison with stator current detection is presented aiming at stator insulation failure, bearing fault, eccentricity and broken rotor bar/end-ring. Although stray flux method is used mostly for induction machine, its potential application in PMSM will be included as well.