Abstract: In order to solve the problem of override trip in high-voltage power supply system of coal mine, a new scheme for preventing override trip was proposed based on optical fiber locking control. Referring to a typical mine power supply system, the short circuit protection principle of high-voltage grid based on optical fiber locking was analyzed. The hardware circuit, as well as the control procedures of protection devices was developed, and the performance experiments were carried on. It has been shown that the scheme can figure out the coordination between switchgears in high-voltage power grid of coal mine by experiments, and can solve the selective problem of over-current protection. In addition, the override trip fault can be prevented effectively. Therefore, with the scheme proposed in this paper, the reliability and safety of the mine power supply system can be improved．