Abstract: This paper analyzes the errors in satellites’ thermal balance test, based on a combined thermal model of the Xiwang-1 satellite thermal balance test (TBT) and the analysis results are compared with the data in the ideal state. The thermal balance test error of Xiwang-1 is 13～20 ℃ in the low temperature case and 12～17 ℃ in the high temperature case; the non-uniformity of the received heat flux on -y cabin panel may reach 27.3% in the high temperature case. Besides, the influences of the temperature, the surface emissivity of the heat sink and the heat sink–satellite surface area ratio, the conduction and radiation heat leak of the bracket and the cable, and the radiometer temperature measurement error on the satellite temperature distributions are analyzed.