Abstract: In this paper,lamination/separation of fractured specimen in steel mechanical tests(tensile test,bend test,compression test,impact test,drop weight tear test and fracture test) are discussed and some viewpoints are proposed,involving the relationship between microstructure and macro crack,identification of lamination and separation,identification of defect and imperfect,rationality of compression test for ship steel as well as the relationship between fitness for service of steel and separation in specimen.