Abstract: This paper presents basic concepts of PETRl net and Knowledge-based Petri Net(KPN),hard-ware condition and for the automation robot planning by KPN in a Flexible Assembly System(FAS),model-ing with KPN and its running for the robot assembling planning. It is discussed in this paper how to establishan adjacency matrix,build AND/OR tree graph,establish a adjacency link lists,build the KPN,and finallyhow to run the KPN.