This paper proposed a pipeline based reconfigurable architecture for CNC controllers. The architecture consists of an upper controller and a NC Microcode Processor (NCMP). The control software in the upper controller is a multi-thread program, including a management thread and a NC pipeline thread. The NC pipeline thread in the upper controller converts the machining program into NC Microcode (NCM), which is optimized for the real-time execution in NCMP. A pipelined feedrate plan algorithm is developed for the proposed architecture. The algorithm features a reconfigurable structure and look-ahead ability for high speed machining. Two prototype systems were built to demonstrate the feasibility of the proposed architecture. The experimental results indicate that the NC pipeline is highly reconfigurable and flexible in design compared to the classic implementation.