Abstract:A scheme of the tailstock NC transformation was introduced to meet the process integrated requirements of the turning and drilling during batch production of some axial parts base on NC lathe SK40P. In this retrofit scheme, the system consisted of PLC, servo drive and servo electric cylinder was used to drive the tailstock, taper shank sleeve and drill in order to further implement the automatic drilling processing of center hole. In the scheme, the masterslave structure was built, the master microcontroller was the original CNC system GSK980TD, the slave was the PLC. The communication between the above was realized by the aid of I/O ports. Practice shows that the retrofit scheme extends the ordinary NC lathe process ability.