In the defense industry, UHMWPE is primarily used as ballistic material because of its light weight, superior mechanical properties, and particularly, its excellent strength-to-weight ratio compared to metal alloys. In this study, the influence of the AWJ process parameters on machining UHMWPE material is investigated. Several UHMWPE plates have been prepared for trimming, pocketing, and hole making experiments using AWJ to understand the process parameter effects on performance measures. The design of experiment method has been used for all experiments and results are analyzed by the analysis of variance and response surface methods. Furthermore, a novel evolutionary optimization method known as particle swarm optimization has been applied to determine trade-offs between the conflicting performance measures of surface roughness and dimensional error in AWJ. With the resulting Pareto optimal solution curve, three industrial scenarios have been developed using k-means clustering algorithm and verified.