The stable and reliable operation of coal mine substation is of great significance to ensure mine safety and improve coal mining efficiency. Taking the substation of Jinbei Coal Industry as the research object, the monitoring system of secondary equipment is designed. The system can be used to monitor the state of the secondary equipment itself and the state of the communication link in real time. Based on the monitoring data and combined with the triangular intuitionistic fuzzy algorithm, the secondary equipment state can be effectively evaluated. Based on the Altova XMLspy software platform and the SCL programming language, the software program of the monitoring system is designed, and the database establishment process used in the software program is analyzed. Practice shows that the monitoring system works well, substation failure rate is reduced by more than 15 %, safety and economic benefits are significant.