Abstract: In the micro-milling process, the radial runout of the micro-milling cutter will reduce the machining accuracy and surface quality, and also reduce the cutting life. In order to reduce the tool diameter runout, based on the idea of on-machine fabrication, the principle of Wire Electric Discharge Grinding (WEDG) processing micro-milling cutter was introduced, and the experimental platform was established. The process and processing parameters of on-machine fabrication micro-milling cutter were designed. A method for detecting the size of the tool in the position of electrical touch is proposed. A micro-milling cutter with a cutter head diameter of 76.59 μm is manufactured by WEDG technology, and an microstructural with average groove width of 78.40 μm and average surface roughness value Ra 77.50 nm are processed.