Abstract: In order to solve the problem of frequency stability and transmission accuracy decrease caused by temperature fluctuation during on-orbit operation of extravehicular load equipment. A thermal control scheme of the extravehicular load equipment is designed using local active electric heating, single-phase fluid cold plate heat exchange and thermoelectric refrigeration technology. In this paper, the finite element method is used to simulate and analyze the temperature distribution in the high and low temperature environment and optimize the design. ±0.5℃ is used to regulate the temperature change of the important components. Finally, it is verified by the ground temperature thermal vacuum test. The results show that the design scheme effectively solves the thermal control problem of the extravehicular load equipment, and provides a reliable guarantee for the space application of high-precision time-frequency transmission technology.