In this paper, the selection and design of the power supply system of the fourth panel of No.15 coal seam in Wenjiazhuang Mine of Shanxi Pingshu Coal Industry Co., Ltd.is carried out. The design adopts double-circuit power supply mode, which is powered by the ground 110/10 kV substation to the underground central substation, sent to the distribution room of the fourth panel through high-voltage cable, and then powered to the mining face. Through the selection and calculation of the power circuit and the dedicated circuit cable, as well as the selection and verification of the high-voltage switch, the stability and reliability of the power supply system are ensured. This paper elaborates the design process and selection basis, and provides technical support for the stable operation of the power supply system in the fourth panel of Pingshu Coal Industry.