This review paper has presented several examples of inductive wear debris sensor. Many of these have important applications in industry. Thus, when monitoring the oil system which operates under extremely severe conditions and various features (size and type) need to detect, it is worth considering the use of inductive wear debris sensor. Based on the electromagnetic field analysis for the coil and particles, three structures of such sensors, classified by the number of coils, are available, and they all can detect, count or classify wear debris. However, the detectable particle size is mainly limited by the background noise. Accordingly, to enhance the sensor performance, the signal processing methods are necessary.