Abandoning traditional flow channels and solving the problem of flow channel patterns, advanced gap mixed flow structure design is adopted to completely eliminate the temperature imbalance caused by traditional flow channels, ensuring that the melt is quickly and uniformly cooled and shaped in the casting process, directly forming high-quality thick sheets with smooth surfaces and uniform thickness. Precision surface treatment ensures cooling efficiency and stability. The cold drum surface has undergone special precision treatment, which has extremely high thermal conductivity and stable cooling efficiency, effectively avoiding defects such as necking and deformation in the forming process of thick sheets, significantly improving the initial forming quality of thick sheets, and laying the foundation for subsequent processes.