Tunlan Mine is a large-scale modernized mine with complex power supply system, many types of power loads and large power. The roadway of 22301 heading face is too long, resulting in large voltage loss of power supply line and low terminal voltage. Through the analysis of the basic working principle and advantages of the reactive power compensation device, the compensation scheme of using static var generator ( SVG ) was determined. The effective data proved that the device can effectively compensate reactive power in the power supply system for long distance mining face, improved the power factor and terminal voltage of power supply system, restrained harmonic pollution and improved power supply quality, which had significant economic and social benefits.