In response to the challenges in measuring safety distances for high-voltage line operations due to small radar cross-sections and low signal-to-noise ratios, where conventional radar methods struggle to achieve reliable detection, this paper proposes a high-voltage line safety distance warning algorithm based on Pulse Coherent Radar (PCR). The algorithm first enhances the signal-to-noise ratio through Multi-Pulse Integration (MPI), then employs a Constant False Alarm Rate (CFAR) algorithm with a fixed threshold for precise target identification. A detection system was constructed, a testing environment was set up, and embedded development of the algorithm was implemented. Simulations and experiments demonstrate that, under low SNR conditions down to -30 dB, small cross-section targets can still be identified. At a detection distance of 5 meters, this method achieves a detection error within 9 cm and a response time below 100 ms, meeting real-time operational and accuracy requirements.