The isomorphism identification of structural type is a vital problem now. For dealing with the isomorphism generated in synthesis of planar configuration based on the synthesis method of Assur- group adjacency matrix,a methodology of Assur- group adjacency matrix isomorphism identification is proposed. First of all,according to the diagonal elements is derived by the amount of Assur- group and active number,the diagonal isomorphism identification is obtained. Then,the condition is classified into three kinds,first is sequence isomorphism when Assur- group is equipped,second is symmetrical configuration isomorphism after adding Assur- group and the last one is discovered in matrix synthesis,which would be recognized and deleted by this method. Finally,the methodology proposed is able to be achieved by computer,easy to control and takes high efficiency in isomorphism identification.