Temperature rise is a major influence factor on the miniaturization and high?load design of DC electromagnetic relays. Thus, accurate temperature rise calculation is an important supplementary means in achieving the performance goals of the relay design. In this paper, a computational fluid dynamics heat dissipation simulation model using fluid?solid coupled heat transfer and discrete coordinate method radiation transfer equations is proposed to improve the accuracy of the original solid thermodynamic finite element heat dissipation simulation model in terms of convection and radiation calculations. The temperature field of a certain type of electromagnetic relay is simulated by adopting the proposed model. Then a temperature rise test is conducted to verify the accuracy of the simulation results. In addition, the temperature distribution simulation results of the relay by adopting the proposed model are closer to the actual situation than that using the solid thermodynamic finite element heat dissipation model. Therefore, the simulation model in this paper can provide a more effective thermal field design tool for the same type of relay products.