Nuclear energy is an integral part of the energy supply required for future space exploration as efficient energy. Although heat pipe reactor is the main development direction of space reactor. Radiation radiator quality accounts for a large proportion of heat pipe reactor quality. Therefore, it is essential to improve the heat dissipation performance of the heat pipe reactor, effectively reducing the quality of the radiator under the condition of ensuring that the radiation heat dissipation power of the radiator is not less than that of the same volume radiator, design the optimal heat pipe cooling scheme and promote the development of space heat pipe reactor. In this paper, based on the finite element multi-physical coupling MOOSE platform, a program is developed to simulate the physical field of the heat pipe reactor radiator. The simulation of the heat pipe, fin and other parts of the radiator end unit is realized, and the combination of heat pipe and fin calculation is completed. At the same time, the temperature field of the new heat pipe radiator unit is obtained. The simulation results for the heat pipe and fin module are verified by the temperature field calculation program and another multi-physical coupling software. Another multi-physical coupling software results are compared with MOOSE simulation results for the combination part. The results show that the MOOSE program can reasonably simulate the heat transfer state in the simulation of heat pipes, fins, and combinations. The temperature field agrees with the verification results.