The technology of space-based wireless power transfer presents a potential solution for supplying energy to spacecraft. However, this method transmits energy through high-power electromagnetic pulses, which may pose a potential threat to gallium arsenide (GaAs) solar cells. Currently, the damage mechanisms affecting solar cells in these conditions remain unclear. To solve this issue, the thermo-electrical coupled damage mechanism of single-junction GaAs solar cells is investigated using a comprehensive multiphysics simulation model in this work. The damage characteristics of the solar cells under varying voltage and frequency inputs are simulated and analyzed. Furthermore, the relationship between burnout time and both input voltage and frequency are investigated, and the differences in damage mechanisms observed at different frequencies are elucidated. The results indicate that due to high current density and contact resistance, burnout mainly occurs at the cathode electrode contacts. Additionally, the PN junction and the anode contact experience significant temperature elevations, which is more likely to affect the cell performance. By deepening our understanding of how high-power electromagnetic pulses damage space solar cells, this study will provide support for designing electromagnetic protection systems for spacecraft power architectures.