Based on the analysis of the power and voltage of the main equipment such as shearer, scraper conveyor, transfer machine and crusher in the 33(4) 20 working face and crossheading of Shuangliu Coal Mine, the number of mobile substations is determined to be 4, and the corresponding apparent power of transformers is 4000, 4000, 2000 and 315 kVA respectively. The power supply system of the working face was designed. According to the actual situation, the high-voltage side cable and the low-voltage side cable were designed and calculated to determine the model. The designed power supply system is applied to the coal mine engineering practice, and the current operation time is more than 1 a. Through the feedback of field personnel, the overall operation of the power supply system is stable, which lays a good foundation for safe and efficient mining.