Abstract: The goal of the Comprehensive Research Facility for Fusion Technology is to build a comprehensive research and testing platform with the highest parameters and the most complete functions in the field of international nuclear fusion, and its cryogenic system includes the cryogenic system of superconducting magnet test device and the research platform for key cryogenic technologies. The supercritical helium circulating pump in the Comprehensive Research Facility for Fusion Technology supercritical helium valve box provides high-flow supercritical helium for the superconducting magnet, and this study focuses on the insulation design for the heat-insulating region of the supercritical helium pump body according to the design requirements. The heat insulation structure of the helium circulation pump is designed, the range of heat sink position is calculated and analyzed, and the heat leakage of the helium circulation pump is accounted for, and the heat insulation performance of the helium circulation pump is numerically simulated by the simulation software ANSYS. The influence of the heat sink position on the heat leakage of the pump body is analyzed. The results show that considering the temperature uniformity and liquid nitrogen consumption, 0.064 m is selected as the heat sink position. In this position, the temperature of the pump body is uniformly distributed, and the temperature of the cold end position is 5.08 K, which meets the temperature requirement of the working medium of the supercritical helium circulating pump. In addition, the main heat leakage in the pump body comes from solid heat conduction. When the heat sink is located at 0.064 m, the gas heat leakage is 0.72 W, the solid heat leakage is 3.66 W, and the total heat leakage is 4.38 W. The total heat leakage obtained by simulation analysis is 8.71 W, which is in line with the heat insulation design index of pump body with heat leakage less than 10 W.