Aiming at the problems of the low machining efficiency and complex clamp adjusting in the process of eccentric shaft, research was carried out. A method was proposed to improve computer numerical control (CNC) grinding machine for machining eccentric shaft by Mitsubishi Robot. The COGNEX three diemnsional (3D) vision system was taken to replace the traditional installation way, a robot control program was designed accordingly to solve the difficult problems such as the automatic load and unload of CNC grinding machine, and the automatic adjustment of distance of eccentric shaft and the communication between the robot and CNC grinding machine. The full automatic machining process of flexible control of eccentric shaft comes true, which greatly improved the machining efficiency and precision of parts.