Due to performance improvement and the trend of miniaturized sizes in optical devices, the need for micro lenses is increasingly presented. In this paper, characteristic study of a micro aspheric mold having a diameter of only 0.3 mm was performed. According to the experimental results of rough cuttings using a diamond tool, the machined surfaces were with a mean peak-to-valley (PV) form error of 1.47 µm. The Taguchi Method was employed to determine the optimal cutting parameters by selecting the cutting depth, work spindle speed, and compensation ratio as the control factors. Experimental trials were conducted according to the L9(34) orthogonal array (OA), and a mean PV form error of 0.79 µm was obtained due to compensation cuttings. Based on signal-to-noise (S/N) ratios, the optimal levels of control factors were determined. By performing the confirmation test, the PV form error was reduced from rough cutting of 1.49 µm to 0.60 μm. The effectiveness of using the Taguchi Method was demonstrated. The systematic approach performed in this paper can be applied to micro-fabrications for precision components in molds and dies industry.