In the brutal temperature environment in moon surface with the range of -180℃ to 90℃,it needs to solve the Lunar-Based Ultraviolet Telescope (LUT) heat dissipation during lunar daytime and heat preservation during moonlit night without electric energy supply.In order to solve the heat consumption transmission,discharge,and the heat preservation problem of moon night,a passive heat pipe thermal switch (HPTS)was proposed as a means of long distance heat transfer between the device and the radiator,according to the phase transition characteristics of the working fluid.Depending on the equipment temperature index,a working fluid with suitable freezing point and heat transfer capacity was selected.The HPTS was filled with working fluid,which can transmit energy from evaporator to condenser by phase-change.In extremely low temperature of the night,the working fluid is frozen,it causes the connection to be interrupted,and then the LUT can be maintained above the survival temperature.It has been proven through the ground test and in-orbit result that the switching ratio of HPTS is greater than 30 near the freezing point.At a working temperature of 7℃,the heat transfer capacity of HPTS is greater than 15W,and heat transfer temperature difference is less than 4℃.In addition,the HPTS can accommodate Lander's tilt of 15°.All the properties of the HPTS ensure that the LUT on Lander works in orbit with high performance.