Abstract: Anti-override trip program for multi-level short line power supply system and its protective action principle were introduced combined transform instance of anti-override trip system of Juji Coal Mine. The program first uses fiber differential protection to transform underground tie-line, then switches to coal mine anti-override trip system based on network intelligent identification by adding communication server. The program completely solves override trip problem of underground power supply system, and does not exist resource waste problem caused by duplicate transformation.