Abstract: In this paper, wxAMPS software is used to build a high-efficiency GaInP/GaAs/Ge solar cell model to study the cell's performance under the electron irradiation. The model is based on the QE data. High-energy particles cause the displacement damage in the solar cells, which is simulated by changing the material parameters. By simulations, the degradation behavior of the solar cells can be determined. The electrical properties of the battery change little under low defect density. However, when the defect density is relatively large, the decrease of the electrical parameters is observed to be proportional to the logarithm of the fluence of 1 MeV electrons. The I-V and QE curves are calculated by wxAMPS. The degradation of the electrical properties, the decrease of the QE, the growth of the reverse saturation current and the increase of the shunt resistance are closely related to each other. Combined with the simulation and the experiment results, the introduced rate of defects for the 1MeV electrons is shown to be about 0.81 when the degradation behavior of each sub cell is supposed to be the same.