Abstract: As a new type reducer, cycloid reducer can be used in gun turret transmission mechanism, industrial robots, CNC machine tools, radar and so on. As the core part of the cycloid reducer, the cycloid eccentric shaft is called "cycloid track generator", which determines the performance of the cycloid reducer, so the machining of the cycloid eccentric shaft becomes one of the key technologies of the cycloid reducer. In order to improve the pass rate of the cycloidal eccentric shaft, the function of the cycloidal eccentric shaft in the phase formation of the cycloidal gear is expounded from the structural form of the cycloidal eccentric shaft, according to the technical requirements of the three-layer eccentric step cycloidal eccentric shaft, the technological process is analyzed, and the precision machining equipment is designed for the forming of the cycloidal eccentric shaft, the key points in the design of special tools are pointed out, and the cycloidal eccentric shaft is machined according to the process cards. The qualified rate of the key dimension of the cycloid eccentric shaft is 100%, which shows the validity of the process and the design of the special tooling.