Abstract: A new method,the so-called graph analysis method （GAM）,is proposed for study of topological equivalence of multistage interconnection netxvorks （MIN’s）.Logical name structures of crossover networks topologically equivalent with a class of MIN’s such as baseline,reverse baseline,Omega,flip,S=F=2 SW banyan,and modified data manipulator are obtained by GAM.Simulation realizations of various interconnection functions of these class of MIN’s by free-space digital optics implementaion of crossover network have been explained,which have potential applications in the fields of multiprocessor system and telecommunication switching system,etc.