Abstract: Aiming at the problems that the traditional offline insulation detection of mining high-voltage cables requires power outage operation, cannot reflect the real-time operation status and is difficult to identify early tiny insulation defects, the design and research of an online monitoring system for mining high-voltage cable insulation were carried out. The open-close magnetic ring coupler was employed to achieve non-invasive signal acquisition, a dual-architecture processing unit （FPGA+MCU） was constructed, the development of high-frequency signal generation, synchronous capture, fault feature extraction and dual-path correction positioning algorithm was completed, and the intrinsically safe explosion-proof hardware circuit and supporting software programs were designed. Experimental tests demonstrated that the system operates within a frequency range of 150 kHz to 15 MHz, with a current monitoring resolution reaching the microampere level, a fault alarm accuracy of 96.7%, and a dual-path correction positioning error of less than 5 m. After three months of continuous on-site operation, the system remained stable and reliable, and could accurately identify insulation degradation trends. This system enables non-invasive, uninterrupted insulation online monitoring, and effectively enhances the fault warning and positioning capabilities of mining high-voltage cables.