As the traditional “one plane and two pins” positioning system would produce larger positioning error, which eventually leaded to insufficient machining accuracy, an automatic control system for “one plane and two pins” accurate positioning was designed. The structure and working principle of this system, and design and calculation methods of main positioning elements were introduced. This accurate positioning system was used in box processing, the positioning error of workpiece was compared with that of the traditional positioning system. The conclusion is that the “one plane and two pins” accurate automatic control positioning system can greatly improve the positioning accuracy and machining efficiency.