Abstract: Heat pipe radiator is widely used in waste heat emission of space system, and its pipe is complex, including heat pipes, fins, cladding and other complex structures. Commercial CFD software and RATHAL code were used to solve the flow and heat transfer problem of heat pipe radiator in the paper. CFD software was used to calculate the flow distribution on the flow pipeline and collector ring, and then the results were imported into RATHAL code to calculate temperature distribution of the radiator. Based on the calculation results, reasonable suggestions for the optimization of the existing structure were proposed for the purpose of uniform temperature distribution. The results show that the combination of CFD software and RATHAL code can simulate the flow and temperature distributions of the radiator as truly and efficiently as possible, and the temperature difference between the collector rings of the radiator is greatly reduced and the design is more reasonable after optimization.