In automated manufacturing systems, Automated Guided Vehicle(AGV) Systems are increasingly important in material handling and manufacturing operations. A considerably flexible AGV system needs to be operated with maximum effectiveness. This paper develops an algorithm for the determination of the entering point and the number of AGVs required in the Flow Shop Type FMS. We consider an AGV used as a carrier and mobile workstation. For the limited number of AGV, the entering point of an AGV on a simple loop is determined in order to maximize the utilization of AGVs. For the unlimited number of AGVs, the number of AGVs required in the FMS is determined on the basis of the entering point of AGVs. The result by the algorithm may be used as a criterion on the control of material flow and the assignment of AGVs in the FMS. A numerical example is given to illustrate the algorithm.