In recent years, heat pipe reactors have attracted much attention because of their simple structure, absence of flowing parts, and adaptability to gravity-free environments. In this paper, the temperature field of core fuel and heat pipe in Kilopower heat pipe reactor is analyzed based on Sinda/Fluint. The pseudo-thermal resistance model is applied to calculate the equivalent thermal conductivity of the heat pipe, and the corresponding thermal calculation models are built for these components in Sinda/Fluint to calculate the relevant temperature field distributions under different operating conditions and obtain the corresponding temperature peaks. Finally, the influence of the heat pipe on the temperature peak is investigated through the related temperature field analysis, which provides reference for further design optimization.