Abstract: Power electronics main circuit devices are the core part of power electronics circuits, and the fault feature extraction（FFE） of power electronics power devices plays an key role in realization of the diagnostics and prognostics of the power electronics converters, which has very important significance for improving the reliability of power electronics equipment. Firstly, the distribution reliability of power electronics devices is shown in the paper, and the failure mechanism and failure feature of active power switches（MOSFET, IGBT） are analyzed. The FFE of the active power switches are classified into two categories: one is the direct extraction and the other is the indirect extraction. Based on the above, the principles of each FFE of MOSFET and IGBT are introduced, and these methods are summarized. In addition, the advantage and disadvantage of each method are also discussed. At last, the difficulties and trends of the research on FFE of power switch devices are indicated.