Abstract: In order to improve the accuracy and reduce the failure risk of temperature control of high-power telecommunication satellite in the thermal vacuum test, a method for the closed-loop temperature control of the heat pipes by using a PID controller is proposed. A thermal vacuum test with the PID self-tuning is carried out for a high-power telecommunication satellite. The PID parameters are determined based on the self-tuning test results. The temperatures of the satellite are controlled by the PID controller through the test. It is shown that the temperature overshoot is less than ±0.5 ℃, which can meet the requirement of the temperature control. The accuracy and the safety of the test are guaranteed over the whole process.