Abstract: The high-speed thin slab continuous casting and rolling production line has developed rapidly due to its short process, low energy consumption, and high output characteristics. It mainly produces a series of steel grades such as low-carbon and low silicon steel, weathering steel, automotive steel, medium carbon steel, and high carbon steel. The high-speed thin slab continuous casting quickly forms a thick enough shell to achieve high casting speed with its excellent mold heat transfer performance. The special shape design of the narrow copper plate meets the concept of no sufficient roller support, but the bulging amount of the narrow surface of the casting billet exacerbates the problems of longitudinal cracking at the edge and folding at the corner during rolling. By developing the narrow surface arc angle mold copper plate process, on the one hand, it fundamentally improves the temperature field of the initial shell corner during solidification in the mold, and on the other hand, weakens it. The stress folding of the protruding corners during the rolling process fundamentally solves the problems of longitudinal cracking at the edges and folding during corner rolling. This article improves the problem of excessive two-dimensional heat transfer at the corner of the casting billet in the mold by developing and applying narrow arc angle copper plates. The average temperature inside the mold is increased by 25.2 ℃, and the form of the casting billet arc angle also reduces the product quality problem of black lines at the edge of the strip steel during the rolling process from the source.