Semiconductor wafer fabrication factories are characterized by re-entrant flows, dynamic and uncertain environments, strict production control requirements and so on. Re-entrant flow means a product routing that consists of multiple visits to a workstation during the manufacturing processes. In this paper, a modeling approach based on generalized stochastic Petri nets is presented. Specifically, a Petri net model representing a re-entrant flow line with three centers and six machines is modeled. Work release policies (WRP) and queuing disciplines (QD) are also added to the model, which take into account the machine preventive maintenance (PM) requirement. Finally, a simulation study is used to analyze the model, which provides support for scheduling decision in shorter time.