According to the MRF process characteristics, a set of control system of the MRF machine with double grinding heads was constructed，which was based on 840D NC system. The main component, functions and software architecture of the control system were introduced. The graphic humanmachine interface was developed using OEM development software and VB, and the double grinding heads combined model control, the grinding head condition monitoring and the grinding head management were realized. The universal automatic control technologies of the MRF special process were developed, such as the workpiece pose measurement, the calibration of ribbon and the polishing spot acquisition. Whats more, the MRF control software and the SINUMERIC 840D NC system were integrated seamlessly. The results show that the control system improves the flexibility, the usability and the reliability of the MRF machine.