Abstract:According to the analysis of the No 1 CCM process and the measures of production, the main causes of longitudinal corner crack in continuous casting slab in No 3 steelmaking plant of Jinan Iron and Steel Co Ltd are the side foot roller clearance, mould cooling and taper, composition of molten steel, superheat degree and casting speed. The rate of slab with longitudinal corer cracks is decreased from 2.77% to 0.09% with the effectual measures.