It is of great significance to study GaN(gallium nitride) power devices and their radiation effects to meet the needs of space applications and promote the construction of a new generation spacecraft. Main structures and working principles of GaN power devices were introduced. Research progress of total ionizing dose effect and single event effect of GaN power devices in recent years was reviewed. Degradation and damage mechanisms of GaN devices caused by radiation effects were analyzed and discussed. Research results show that GaN power devices have strong resistance to total ionizing dose. However, GaN power devices are prone to leakage and single event burnout due to their weak resistance to single event burnout, and most of the burnout points occur at the drain side of the gate edge. Research on the radiation damage mechanism of GaN power devices lacks authoritative theories and needs to be further mastered to provide theoretical support for their space application. GaN power devices with planar structure are the current mainstream technical solutions. Monolithic integration, high frequency and miniaturization are the development directions of GaN power devices in the future.