Abstract: In this paper, the reactive power compensation device based on proportional resonance control algorithm is used to solve the power quality problem of power grid. This paper analyzes the proportional resonance control algorithm and the principle of reactive power compensation device. Comparison and analysis of power factor, voltage, current and harmonics of power grid before and after equipment input in a mine. The effect of this device on improving the power quality, increasing the power factor and saving energy consumption of low voltage power supply system in coal mine underground is verified.