Abstract: Based on the structure and the thermal-stress properties of materials of mercury cadmium telluride(MCT) infrared focal plane array detector (IRFPA), the damage mechanism of MCT IRFPA caused by laser irradiation was elaborated. Based on the relevant irradiation environment and conditions, a three-dimensional simulation model was established by finite element analysis. Based on COMSOL Multiphysics software, the temperature changes and stress changes of various parts of MCT detector were detected, when irradiated by 10.6 μm laser. The numerical analysis method was used to compare the temperature field changes and stress field changes along the surface radial and internal axial directions of the MCT detector after laser irradiation with different spot power.The numerical analysis method was used to compare the spot area of MCT detectors. Temperature field changes and stress field changes in the radial and internal axial directions of lasers with a constant irradiated area and different constant powers.The simulation results show that the surface temperature and stress of the MCT detector increase rapidly after continuous laser irradiation of 10⁶ W/cm², causing damage to the detector surface.Meanwhile, the temperature change of the irradiated part of the detector also causes the internal local stress value to change.Through comparing the stress damage threshold and variation trend of the MCT detector with the experimental data in the literature referenced, it is found that the results are basically the same, the feasibility of the model can be verified.