Abstract:ServoWorks is a solution of open CNC system software based on PC, which all the functions are accomplished by software. Through the analysis of the hardware structure and software structure of ServoWorks CNC system, many advantages of open CNC system were understanded, and on the basis of SDK development kit for software which was provided by Soft Servo System company, the research and development of four axis linkage numerical control system software was completed in VB60, and the software was tested in the the four axis machine tools and achieved the expected effect.