Abstract: Tests were carried out on the polyimide-film heater heating circuit with the tinned copper wires. The heat resisting performance of every part of the heating circuit under different high temperature conditions in the vacuum environment was analyzed, including the insulation performance between the circuit and the structure. The test results show that the heating circuit itself will not have a short circuit when the temperate is under 350 ℃. The weak points for the heat resisting are the wires and the welding spots. In the end, the improvements to strengthen the heating circuit's heat resisting performance are suggested.