Abstract: With the extension of underground coal mine power supply distance, the voltage loss on the cable line is more and more serious, which affects the normal operation of the power equipment at the end of the line, especially the normal operation of the asynchronous motor, resulting in motor starting difficulty, undervoltage operation, and the actual power factor is reduced. To address this problem, we take a long-distance power supply system of a tunneling face in Baotou Wanli Mine as an example, analyze the current situation of system voltage loss and power factor, and finally put forward a comprehensive voltage regulation scheme based on the compensation and voltage regulation structure of “autotransformer+compensating regulator+compensating transformer” by comparing a variety of voltage regulating schemes. By measuring the electrical parameters on the power side of the line, the end voltage of the line is deduced, and then PLC controls the compensation regulator brushes according to the set value of the end voltage to carry out compensation and voltage regulation, which stabilizes the end voltage of the line and improves the load carrying capacity and power factor.