The reconfiguration technology of CNC system is divided into two interactive levels: hardware system reconfiguration and software system reconfiguration. The hardware system reconfiguration is based on a rapid field programming of Field which is performed with different FPGA configuration files. Meanwhile, software system reconfiguration is conducted through design, modification, selection and configuration of different databases on a guiding software reconfiguration development platform. Then, the software-hardware co-design of the system reconfiguration is discussed. Finally, an application case of aforementioned reconfiguration methods is given. A CNC system with 5 synchronously moveable axes in total 8 stepping axes is reconfigured successfully from the existing CNC system with 3 synchronously moveable axes in 4 ones.