To describe a semiconductor wafer fabrication flow availably, a new modeling method of extended hybrid Petri nets(EHPNs) was proposed. To model the discrete part and continuous part of a complex photolithography process, hybrid Petri nets(HPNs) were introduced. To cope with the complexity of a photolithography process, object-oriented methods such as encapsulation and classifications were integrated with HPN models. EHPN definitions were presented on the basis of HPN models and object-oriented methods. Object-oriented hybrid Petri subnet models were developed for each typical physical object and an EHPN modeling procedure steps were structured. To demonstrate the feasibility and validity of the proposed modeling method, a real wafer photolithography case was used to illustrate the modeling procedure. The modeling results indicate that the EHPNs can deal with the dynamic modeling of a complex photolithography process effectively.