Abstract: Main causes of override trip accident of coal mine power supply system were analyzed, which included short circuit, leakage, voltage fluctuation, switch operation rejection, etc. Both advantages and disadvantages of existing anti-override trip methods of coal mine power supply system were pointed out including fiber-optic current differential protection, junction locking and centralized control. An anti-override trip monitoring system of coal mine power supply was proposed and structure and functions of the system were introduced. The system adopts an anti-override trip solution scheme named three dimensions and an entirety, which prevents override trip of the power supply system from three dimensions of short circuit, leakage and voltage fluctuation, and fuses anti-override trip protection and common protection, anti-override trip network and fiber-optic ring network, and anti-override trip monitoring and power supply monitoring into an entirety, so as to improve reliability of anti-override trip of the system. The application result verifies selectivity, rapidity and reliability of the system about anti-override trip.