||Traditional control system design can’t fulfill the needs in mass customization manufacturing (MCM). Under MCM, programmable logic controller (PLC) should be reconfigurable to execute multiple material routings, to deliver parts/tools to different workstations. However, traditional PLC program design only support one control operation, which is inflexible to be reconfigured frequently at system run time. Regenerating PLC code for every change in control operation will result in significant efficiency lost. In this thesis, the reconfigurable control system design is presented. Reconfigurable Programmable Logic Controller (PLC) programs, based on PLC Statechart and design methodology in (Schreyer M. H., 200l), are developed for the controls in mass customization manufacturing. All feasible operations that PLC should execute are identified and programmed in PLC. The PLC response can be altered online, by triggering the control logic for the pending operation. PLC program reconfiguration can be achieved without code download and system shut down, thus enhancing the control system efficiency. The reconfigurable control system design has been implemented in the design of a Flexible Assembling System (FAS) control system. Reconfigurable PLC program was developed for the control of flexible material routing system. With the high speed reconfiguration process, PLC program can be reconfigured to execute various material routings according to shop-floor condition and the assembling process of every customized product. With the existing PLC program design methodology, engineers often need minimum 2 to 3 days to modify PLC program for new material routing requirement. Now, with a systematic reconfigurable PLC program approach, the PLC takes maximum 6 seconds to be reconfigured to new material routing.