Abstract: In need of the design of the spacecraft thermal control,thermal contact resistance（TCR）of copper to copper joints has been measured in vacuum,when the interfacial temperature is 110 K.The influence of different screw preload torque and different thermal conductance fillers to the TCR has been compared.The experimental data indicated that the TCR decreases by the first order exponential decay while the screw preload torque increases,the indium foils exhibits the best performance to degrade the TCR,the lowest value of TCR can be 2.0×10^-5 K·m²/W.