The development of Single Point Diamond Turning (SPDT) technique provided technologic and technical base for the mass production and application of aluminum mirrors. To ensure the image quality of the optical system, stress-caused distortion of reflective surface by mounting pretension stress and uneven mounting surfaces needed to be attenuated. Multiple typical structural shapes of the stress-relief support were demonstrated and the design principle was summarized. The SPDT technique created a new technical route to aid the optical assembly process. The design of assembly assisted by SPDT was showed in instances of reflective surfaces on unilateral side and bilateral sides in single mirror and detached double mirrors. The integral SPDT machining flow of optical surfaces, structural mounting surfaces, transferring datum and reference surfaces of interference detection linking with concrete examples implemented the transfer of high-precision assembly reference and ensured high-accuracy alignment of mirrors. This method could improve the assembly efficiency and shorten the manufacture period of optical systems.