Abstract: Light-emitting diodes (LEDs) as keydevices in the fields of space exploration and nuclear technology hold broad application prospects. However, in space applications, LEDs face challenges from the radiation environment, which poses a serious threat to their reliable in-orbit operation. Thus, studying the irradiation effects of these devices is of great significance. To ensure the reliability of gallium nitride (GaN)-based LEDs in the space radiation environment, GaN-based LEDs were focused on, and a device physical model as well as a single-event irradiation damage model were established via the Sentaurus TCAD simulation platform in this study. In the simulations, single-event transients (SETs) of the device were investigated under different linear energy transfer (LET), incident angles, and incident depths to simulate LED damage under various irradiation conditions. The transient waveforms of the cathode current, internal electron current density of the device, and the temporal evolution of the current density were analyzed in depth. The simulation results indicate that: 1) The single-event sensitive region of the LED is mainly concentrated in the PN junction light-emitting area and the electrode contact layer; 2) The single-event transient peak increases with the increase of LET, and the peak of the single-event transient pulse reaches 150 mA at LET of 75 MeV∙cm²/mg; 3) When the incident angle is 30°, the particle path overlaps with the sensitive region, resulting in the most significant transient change in electron density and the highest sensitivity to single-event incidence; 4) With the increase of incident depth, the particle endpoint locates in the LED substrate, which enhances charge collection and leads to the highest sensitivity to single-event incidence; 5) As the incident depth further increases, charge collection is further enhanced, and the single-event transient pulse continues to increase. Furthermore, the results reveal that interface trap charges and carrier leakage effects are the primary causes of LED performance degradation. This simulation study not only clarifies the damage mechanism of LEDs under single-event irradiation but also provides a theoretical basis and methodological support for an in-depth understanding of irradiation damage effects. By further optimizing the device structure and material properties, it is anticipated that the reliability and stability of GaN-based LEDs under extreme irradiation environments can be improved, thereby facilitating their wide application in space exploration and nuclear technology.