An open double coordinates computer numerical control (CNC) system was developed, which was based on PC and PMAC motion controller card. A miniature and teaching CNC lathe machine was developed with a simple structure, low cost, small volume and suitability for teaching. The CNC system had the advantages of 2-axis linkage, program editing, manual operation, inching operation, simulation processing operation, automatic operation and dynamic display of the tracing. The system was based on the Windows XP platform. Its interface was friendly and it was convenient to manipulate.