In order to study the frictional torque characteristics of the space slip ring in the thermal vacuum test,the frictional torque characteristics of the ringblush pairs and the bearing pairs were analyzed from the vacuum and temperature combined with the theory of sliding electric contact and the theory of tribology.The analysis results show that the vacuum environment mainly affect the friction interface characteristics of the ringblush pairs,resulting in the increase of friction coefficient of the friction pairs and the increase of frictional torque.The high and low temperature environment mainly affect the preload of the bearing.The high temperature has a small impact on the preload,while low temperature results in a significant increase in the preload and frictional torque.The friction torque testing system was constructed to verify the analysis results.The experimental results show that the frictional torque under the high and low temperature vacuum environment is 1.2 and 1.4 times of the frictional torque under the atmospheric pressure.The friction torque of bearing have greatly influence on the slip ring than the ringblush.