Abstract: Taking a power amplifier module as the research object, one conventional structure and three optimized structures for heat dissipation were designed. Under the condition of the same fan, the same initial, and the same boundary condition, numerical simulations were respectively conducted on the heat dissipation of the four structures based on thermal simulation technology. Simulation results show that, the heat resistance inside the module and the heat flux density at the bottom of the module both can be decreased by the optimization of the module structure, while the convective heat transfer coefficient of the radiator can be improved by the optimization of the radiator structure. Both of the above two optimization measures can reduce the heat source temperature, and the optimal effect of the heat dissipation can be obtained with the combined two measures.