Edge longitudinal cracksEdge longitudinal crack are common defects in the hot rollingHot rolling process of thin slabsThin slab, which are difficult to removeRemove by surface cleaning, and will reduce the yield of plate. Folding of the edges was usually caused by the combined action of the vertical and horizontal rollers. To investigate the evolution of crackCrack and edge during thin slabThin slab reciprocating longitudinal rollingLongitudinal rolling process, the physical model of slab rolling process was developed. The shape of the edge of the intermediate slab was investigated. The extension of crackCrack particles prefabricated 2, 3, 5, and 10 mm below the slab surface was also discussed. Research shows that under the combined action of horizontal and vertical rollers, the width and thickness of the plate are decreased. Material within 5 mm of the narrow side corners will extend to the wide side of plate, and folding is found in the newly generated corners. After finish rolling, cracksCrack within 3 mm below the slab surface will extend to 0.15 mm below the plate surface and 0.04 mm at corners. These cracksCrack may be removed by surface cleaning. Deeper cracksCrack will not be removed, although the depth from the surface is reduced.