Abstract: Formalized description of reconfigurable manufacturing system （RcMS） is presented to serve as the theoretical basis for system optimization.Timed reconfigurable Petri net（TRPN） is introduced to model the whole system.Case study of an example with given machine tool facilities and production program illustrates the way of constructing and running the TRPN.Reconfiguration algorithm is formulated to make the system adapt to the changing of production program.