Abstract: In the process of machining thin-walled parts, the clamping deformation, process deformation and other issues have been affecting the machining precision and efficiency, this paper studies the one ring thin-wall aluminum alloy parts of NC machining process, to solve the problem of poor rigidity, easy to deformation of the parts, to reserve a supporting body and design way to suppress the deformation of the special fixture parts, finite element analysis proves the rationality; A reasonable NC machining process is developed, and the part is simulated in Vericut by UG programming. Finally, the actual processing is carried out on the machine tool. The results show that high machining accuracy can be obtained.