The total thermal resistance of a straight heat pipe heat transfer system at room temperature is studied experimentally. The total thermal resistance of the heap pipe and the resistances of heat pipe and heat-end and cold-end mounting surfaces when the system is installed with different torques are analyzed mainly. The research result shows that test environment has a certain influence on the heat transfer capability of the system. The thermal resistances of the heat-end and cold-end mounting surfaces are greater in vacuum than those in atmosphere. The mounting torque of the screw used may affect the thermal resistances of contact surfaces. In both environments, the thermal resistance of the cold-end mounting surface with a torque of 0.4 Nm is about 2.4 times greater than that of it with a torque of 1.2 Nm under a certain heat load.