The impeller and the main shaft of the turbojet engine compressor were joined together in an interference fit manner. A reasonable magnitude of interference could not only prevents the relative slippage between the compressor impeller and the main shaft, but also guaranteed that the temperature difference method did not damage the impeller and main shaft material. Using software Ansys, the substructure model was used to analyze the relationship between magnitude of interference and assembly stress, frictional coefficient and rotor stress, rotation rate and interface pressure, and the distribution of contact stress along the axial direction. The reasonable magnitude of interference was obtained by temperature difference method, and the conical interference surface model was proposed for the first time, which had guiding function for the architectural design of turbojet engine.