Abstract: In the production practice, when the plexiglass parts are in a constrained state, plastic deformation is easy to occur due to the large temperature difference in the environment, so that the product is unqualified and discarded. In this paper, the machining technology of plexiglass parts used in the constrained state is studied, focusing on the process improvement, optimization and experimental verification for the machining technology process of the disc-shaped plexiglass piece under a constrained state during the machining process of "tray component". Finally, the machining process plan for the plexiglass parts in constrained state is obtained, and then the feasibility of the machining process plan is verified in the actual production. This scheme has guiding significance for the processing of plexiglass parts in both free state and constrained state, and it has certain popularization value.