Abstract: The Stirling thermoelectric conversion system has broad prospects and can efficiently convert the heat in the reactor into electrical energy, making it an excellent solution to energy problems in current high-power space projects. The use of special-shaped water heat pipes as the waste heat removal part of the Stirling cold end has high research and application value. This experiment takes the special-shaped curved water heat pipe designed for Stirling cold end as the research object, and conducts analysis on the optimal liquid filling amount, reverse gravity inclination angle, start-up and heat transfer characteristics. The experiment results determine that the optimal liquid filling amount for the sample is 130% of the theoretical liquid filling amount (35.0 g). Explored the range of inclination angles at which the heat pipe can operate normally under reverse gravity conditions during operation, it is concluded through experiments that the heat pipe can fully start at around 75 ℃. The ranges of reverse gravity inclination angles that can operate normally at working temperatures of 85, 95, 105, 115, and 125 ℃ are 0°-7 °, 0°-7 °, 0°-5°, 0°-4°, and 0°-4°, respectively. In the heat transfer characteristic test, the heat pipe was subjected to different cooling conditions (vacuum, pure Ar, 50%Ar+50%He and pure He) within the working temperature range of 120-130 ℃, and the heat transfer power at around 125 ℃ was taken as the comparative analysis object. The corresponding results are 51.3, 110.7, 150.9, and 221.3 W, respectively. This study determines the optimal liquid filling amount for the special-shaped curved water heat pipe and the range of inclination angles that can operate normally under reverse gravity conditions. The heat transfer characteristics of the heat pipe under different cooling conditions were studied, and the optimal heat transfer power for cooling at a specified temperature was obtained, demonstrating the high thermal conductivity and efficiency of the heat pipe. This has important reference significance and value for the design and use of formal samples of special-shaped curved heat pipes for Stirling cold ends.