Abstract: According to electromagnetic coupling relationship between metal wear particles and inductive coil, a novel inductive wear particle sensor and the detection system were designated. The testing bed of on-line wear particle monitoring was applied to verify the capability and conformity. And the relationship between the outputs of the detection system and the speeds of the wear particles was also studied. The experimental results showed that the sensor was effective to detect Fe wear debris with sizes larger than 100μm and Cu wear debris with sizes larger than 500μm. The magnetic particles trap can remarkably improve the detection capability of the sensor for small ferromagnetic wear particles. When the speed of wear particles was fixed, the sensor had good consistency for different kinds of wear particles of different sizes. The speed of wear particle had a great effect on the output of the detection system. And the output decreased quickly by decreasing the speed of wear particles. The responsing speed of the detection system can be improved by increasing the frequency response of the signal amplifying circuit. The conclusions of this study was that the sensor can meet the requirement of on-line monitoring of wear particle in oil.