To solve the problems of low precision and poor reliability of traditional contact sensors in the detection of high?voltage cable suspension, a non?contact displacement detection system of high?voltage cable suspension differential mutual inductance is developed by applying the principle of electromagnetic induction and adopting the differential mutual inductance measurement technology through the coordinated work of the transmitting circuit and receiving circuit, which realizes the high?precision detection of the position of the cable core. The transmitting circuit drives the transmitting coil by enhancing the 85 kHz sinusoidal signal, and the receiving circuit converts the received signal into ± 5 V direct voltage signal and 4 ~ 20 mA current signal. To effectively suppress the radiated interference, which is mainly concentrated in the receiving coil and its transmission path, a combination of shielded transmission line and band?pass filter is used to minimize the noise effect. The experimental results show that the best performance of sensor linearity and sensitivity is achieved in the displacement range of ± 30 mm, with linearity up to 97.49% and sensitivity up to 35.93 mV / mm. This system significantly improves the detection accuracy of high?voltage cables, overcomes the limitations of the traditional detection methods, and demonstrates good stability and reliability.