Abstract: In the parallel development of the twin Beidou-3 MEO satellites, a test scheme of “the two satellites entering the same tank at the same time, the thermal balance test for a single satellite, and the thermal vacuum test for the both satellites” is proposed with a careful consideration of the overall mission requirements, the thermal control characteristics and schemes of the satellites, as well as and the existing test conditions. Meanwhile, the additional heat flow caused by the shielding between the two satellites is corrected through a simulation analysis. The thermal balance test and the thermal vacuum test can be simultaneously completed in the same vacuum tank at one time. The flight data in orbit show that the thermal balance test result can be used for predicting the temperature of the satellites in orbit with a good accuracy, thus it can be said that the parallel vacuum thermal test method is practical.