Abstract: In accordance with the new requirement of temperature control in satellite vacuum thermal test, the relationship between the control parameter and the set value is analyzed. It is indicated that the relationship between the proportional gain Kc and the set value is approximately directly proportional, the integral time Ti can be selected as a constant, and the differential time Td can be neglected because of its little effect. These parameter selection methods and rules can be used before vacuum thermal test. The control parameter can be obtained through the thermal response test before the test. This method can improve the closed-loop temperature control performance, thus increase the automation level, the stability and reliability of the temperature control system.