Abstract: Power supply system of coal mine in China is given priority to single end radial power supply generally, which is mainly composed of substation ground, underground central substation, substation of mining area and the distribution point, with complex power supply system, multi series, frequently overstep tripping phenomenon. The system for preventing override trip of regional centralized mine intelligent substation based on differential protection, combined with the advantages of sampling value differential protection, based on sampling differential protection of sudden current change, improves the reliability of the system under the premise of ensuring rapidity. Finally, we analyze and calculate the network transmission delay for the system, which shows that the system meets the requirements of communication by OPNET simulation.