The change of temperature in satellite have a direct influence on the performance of electrical devices. Aiming at studying the performance of electrical devices due to temperature distribution of radiant plate, the mechanism of temperature dissipation of the radiant plate was analyzed based on its characteristics. The research on thermal effect of laser irradiation in a simplified model of radiant plate was done by using the finite element analysis software. The transient temperature distribution under pulsed laser radiation was got by numerical simulation of the surface temperature field. The pulsed laser was used as the radiation source to irradiate the radiant plate, based on analysis and study of the simulation results, it was founded that the temperature of the electronic device would rise by 64.5 K when there was no heat dissipation around the electrical devices. When the heat pipe radiator was in the maximum working performance, the thermal effect of pulsed laser irradiation would seriously affect the heat dissipation performance of the heat pipe, the abnormal work of the heat pipe would increase the temperature of the electronic device and affected the normal operation of the electronic devices. It lays a theoretical foundation for the influence of the temperature on the performance of electronic devices.