Abstract: We have proposed a method of non-fixed ring belt random double-side polishing based on the technology of translational pendulum. A device based on translation and pendulum out of limits to fixed ring belt was designed. The iterations were carried out by random motion which solved the periodic trajectory problem in the process of fixed ring belt polishing. We developed a device coupling with double-side polishing based on active translation and pendulum. We have achieved stable control of the large-aperture ultra-thin component surface shape in the random motion superposition by optimizing the combination of movement mode. Compared with planetary double-side polishing, our method not only has better surface shape, but also has no obvious periodic processing trace. The method can be applied to batch production of ultra-thin parts with special requirements for laser damage threshold of surface.