This research presents a process of micro spherical tool with an innovative helical insulating layer by using electrophoretic deposition and electrical discharge machining. The solution of methanol with silicon of carbide miniature powder was adopted by electrophoretic deposition method and the thickness variations of deposited layer on the micro spherical tool was discussed via various electrophoresis parameter as silicon carbide concentration, deposition voltage, deposition time and pulling speed to realize the influences of the coating layer. The objective of this paper is to develop an excellent micro spherical tool with high machining performance. The coated micro spherical tool will also be tested to know its machining performance such as electrochemical machining in the future.