Abstract: Based on the accurate location of surface defects from casting slab to rolled metal, the corresponding relationship of defects between casting slab and rolled metal were researched in order to find out the causes of defects and improve process in time and more precisely. And the evolution behavior of subsurface bubbles of casting slabs during rolling process was systematically studied, and the patterns of the defects were analyzed. The results show that the defect location method for the surface defects from casting slabs to rolled metal can accurately locate the surface defects of rolled metal. The surface cracks of rolled metal corresponding to subsurface bubbles of casting slabs are shorter and have the following features. Both tips flocking together, no obvious transition, oxide in the cracks, no abnormal rheology of microstructure near the cracks, and obvious decarburization, which can provide scientific basis for improving the surface quality of casting slabs.