Based on the mechanical study of the ultrasonic magnetic abrasive finishing (UMAF) and analyzing the mathematics cutting model of the traditional magnetic abrasive finishing (MAF), the effects of the ultrasonic vibration on the finishing efficiency of the traditional MAF was discussed. It has been found that the process parameters, the spindle speed, the ultrasonic vibration power as well as the gap between the magnetic pole and the work piece surface, were the key factors in deciding the finishing quality and efficiency of the UMAF. Then, with a numerical control machine and its NC codes for machining a free surface of a work piece, by the software and database technologies, a new control system was designed which could control the process parameters in the UMAF polishing proceeding. Finally, the experiments have showed that the system could implement the UMAF control automatically.