In this study, according to the simulation of the relationship among the elemental work time, cycle time, the ratio of priority and the line balancing efficiency, a system with the minimum number of work stations is searched. It is confirmed that a samller elemental work time as compared with cycle time and a lower ratio of priority make a higher possibility of a system with the minimum number of work staions. In case the system is impossible, a system with the minimum number of work stations accomplished by enlarging some work stations and an economical formula for the system are presented.