This study aims at producing an optimal cutting-parameter design for a finishing process for high-speed end milling using Taguchi-principle component analysis. The workpiece materials is SKD61 tool steel. The major performance indices chosen to evaluate the workpiece quality are surface roughness and surface waviness. The Taguchi method was used to produce parameter design for all experimental trials and the multiple performance characteristics (MPC) were evaluated using S/N ratio. The principle component analysis (PCA) was then used to convert the MPC into a single performance index. The Optimum design can be found by the analysis of variance and control factors response table on the single performance index. The confirmation results show that the surface roughness and surface waviness were significantly improved by the optimum design predicted by the Taguchi-PCA method.