Abstract: The breaker often took place unselective overstep tripping when short circuit fault occurred in mine high-voltage power network, which is a technical problems and potential safety hazard of underground power supply existed for a long time. The paper used the correspondent relation between modulus maximum of wavelet transform and traveling wave singularity point to measure time of arriving protection installation of traveling wave, then calculated traveling wave speed under particular frequency of the cable in real time for accurate fault location. It made use of action time of protection increasing with fault distance to construct a fast and selective longitudinal protection system by microcomputer’s logic judgment, which is not influenced by protections’ interlock.