Abstract: In view of the traditional maintenance issues of relay protection devices in coal mine substations, such as high labor intensity, difficulty in troubleshooting, low maintenance efficiency and long time consuming, This paper presents intelligent display and maintenance system of relay protection device, The best maintenance cycle model and database of the relay protection device are built, Using Matlab to analyze the fault characteristics of the relay protection device.The results show that the failure will occur when the mechanical equipment deteriorating in different degrees, the failure strength of the relay device increases over time, equipment is in a state of gradual deterioration, and the best maintenance period of the equipment is 3.2 years.Field application of the relay protection device intelligent maintenance system shows that the intelligent maintenance system can evaluate the equipment status, predict the deterioration trend of relay protection equipment, timely find potential faults, accurate positioning maintenance, thus greatly improve maintenance efficiency, shorten the troubleshooting time, improve the stability of the power supply system.