A Micro WEDM (Micro Wire Electrical Discharge Machining) CNC system is presented in this paper. Its hardware platform adopted PC with movement control card. For Micro WEDM system is a typical multitasking and real-time system, the CNC software adopted multithread and module structure to perform the parallel tasks and real-time tasks. It also adopted fuzzy control algorithm to control the feeding speed and acceleration. Practical proved that the CNC system is not only low cost and easy to development, but also satisfied the need of Micro WEDM.