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 address this issue, this study investigates the thermo-electrical coupled damage mechanism of single-junction GaAs solar cells using a comprehensive multiphysics simulation model. The simulations analyze the damage characteristics of the solar cells under varying voltage and frequency inputs. Furthermore, this work investigates the relationship between burnout time and both input voltage and frequency, while also elucidating the differences in damage mechanisms observed under different frequencies. Results indicate that burnout predominantly occurs at the cathode electrode contacts due to high current density and contact resistance. Additionally, the PN junction and the anode contact experience significant temperature elevations, potentially impacting the cell performance. By enhancing the comprehension of how high-power electromagnetic pulses damage space solar cells, this study will support the design of electromagnetic protection systems for spacecraft power architectures.