Abstract: This work proposes a two-electron resonance absorption (TERA) model, which explains the reason for laser-induced single event upset (SEU): when the energy of a single photon is not enough to excite the electron-hole pair, there will be de-excitation from a free-electron with higher energy in the conduction band to provide extra energy to excite the electrons in the valence band to the conductive band. This model can explain the physical mechanism of the material’s absorption of photons in the laser-semiconductor material interaction and explain the effect of the ambient temperature and doping concentration of the material on the absorption coefficient through the importance of the concentration of high-energy electrons in the conduction band for TERA. In our simulation, we use laser as the energy source for the thermal spike model, and the spatial-temporal evolution of the electronic temperature in the material during the laser radiation is simulated. Therefore, the change in absorption coefficient can be explained by the TERA. Moreover, according to the Fermi-Dirac distribution, the free charge density is calculated by the electronic temperature of the material. Furthermore, the accumulated free charge induced by laser radiation is given by the integration over the whole volume of the material. Thus, the numerical solution of the charge excitation process is obtained, through which the total amount of excitation charge when the laser induces SEU can be calculated. The simulation results show that the relationship between laser energy and the total excitation charge is nonlinear, i.e., there is a nonlinear correspondence between laser energy and the linear energy transport of particles, which is consistent with the experimental results.