Abstract: In order to determine the ultimate thermal control capacity of a certain spacecraft transport package at the typical high temperature, the test schemes about the active heat control and the passive heat preservation are designed, respectively, and the related experimental research is carried out. The results show that the solar radiation is the primary factor affecting the temperature of the transport package; the ambient temperature is the secondary factor. Under the active refrigeration condition where the ambient temperature is about 40 ℃ and the initial temperature of the internal spacecraft is about 30 ℃, the transport package is capable of controlling the spacecraft temperature in the required range below 40 ℃ with a margin of nearly 7 ℃. Under the passive heat preservation condition where the ambient temperature is about 35 ℃ and the initial temperature of the internal spacecraft is about 25 ℃, the transport package can keep the internal spacecraft temperature below 40 ℃ for about 2 h 15 min. A series of measures and suggestions are put forward for avoiding the direct sunlight exposure and increasing the forced air convection of the transport package for further reducing the risk of the temperature control during transportation and thus enhancing the thermal control capacity.