One of the finish processing methods for hard-to-machine metallic alloys is grinding. Before grinding, the dressing is required to ensure the precise grinding. Dressing is a vital stage in the grinding process to ensure a consistent wheel topography and performance. This study refers to the influences of the dressing parameters as the depth of dressing cut, the rate of dressing feed and the speed of grinding wheel when grinding sharpen convex surface by CBN wheel on CNC milling machine. The Taguchi technique and analysis of variance (ANOVA) are used to identify the impact of dressing regime parameters on the dimensional tolerance. The experimental results show that the impact level of the wheel speed (Rpm), the feed rate (Fe), the cutting depth (aed) and errors on dimensional tolerance (Tol) are 66.02%, 27.43%, 1.98% and 13.64%, respectively. With the optimum dressing parameters as the cutting depth of 0.02 mm, the wheel speed of 1000 rpm and the feed rate of 600 mm/min, the dimensional tolerance of the part is the smallest