Abstract: The layout design of manufacturing systems has long been recognized as one of the most critical and difficult design tasks in manufacturing industries. A solution strategy combining optimization modeling with virtual reality technique is proposed so that the layout design problem of machines in a unidirectional loop manufacturing system is better solved. The important properties of this unidirectional loop layout problem are studied and three new properties are presented. Based on these characterizations, a new heuristic algorithm is proposed to solve such NP-complete layout problems. Furthermore, an example of the immersive VR application of the machine layout is examined.