Abstract: An improved particle swarm optimization method for milling parameters of ring thin-walled parts was proposed to address the issue of excessive local deformation of a ring thin-walled part during machining. By using finite element software, the simulation of the region with large local deformation is carried out to obtain the simulated milling force, and the objective function between the machining parameters and the milling force is established using Design- Expert13's orthogonal experimental response surface method. The improved particle swarm optimization algorithm is then used to optimize the objective function. Finally, the results demonstrate that the method of milling parameters optimization of annular thin-walled parts with an improved particle swarm algorithm can reduce the milling force in this region of the part with large local deformation by 24.9%, effectively reducing the deformation of annular thin-walled parts, and providing a new reference scheme for technicians in selecting milling parameters for annular thin-walled parts.