Various chips and storage devices are widely used in microcomputer relay protection devices. A failure of the device will affect the stable operation of the power system. The cause of the protection device action, combined with a malfunction of the protection device caused by a single event upset is analyzed, and the problem of single event upset is determined. The mechanism, characteristics and effects of the single event upset are analyzed, and a complete method to tackle this based on chip selection, hardware architecture, software architecture, etc. is proposed. The solution proposed in the paper is applied to the design of a relay protection device. It can effectively reduce the impact of a single event upset on a relay protection device. This is of significance for the stable and safe operation of relay protection devices and power systems. This work is supported by the National Key Research and Development Program of China (No. 2018YFB0904900 and No. 2018YFB0904903).