Abstract: The infrared heating cage is often used as the external heat flux simulation device in the thermal vacuum test (TBT& TVT) for spacecraft. To conduct an accurate simulation of the heat flux, the infrared heating tape array is supposed to cover the whole surface of the spacecraft. To solve the difficulties in confirming the structural matching degree between the spacecraft and the infrared heating cage in the test, a set of digital structure matching methods is adopted based on the 3D scanning technology. The set of methods is successful in reducing the accumulated error during the data splicing and in optimizing the parameters of the 3D scanner. The total geometric error of the 3D scanning and the reverse modeling is not more than 10 mm. By using this set of methods, the structural matching is completely achieved between the heat flux simulation device and the spacecraft. In the meantime, the actual installation state is in good agreement with the simulation results.