When a high-frequency alternating current is used to stimulate a three-coil inductive wear particle sensor when wear debris is passing by, a weak inductive electromotive force signal will be produced. Due to the effect of mutual inductance, the inductive coil produces a mutual inductive electromotive force, which brings in high levels of interference. An approach to eliminating this interference and extracting a high signal-to-noise ratio inductive electromotive force signal is of great significance in particle recognition, particle counting and fault estimation. The mathematical model of the sensor using the mutual inductance principle and the concept of wear inductive electromotive force is introduced. Then, the model of wear electromotive force extraction method is established based on the lock-in amplifier principle. Finally, the simulation and the experimental results validate the correctness of the model when the electromotive force signals are successfully separated, and provide the reference for the type of sensor design.