Ultra-thick plates are necessary for shipbuilding, marine application, energy & petrochemical and high-rise buildings. The conventional process of producing ultra-thick plate (≥100mm) is characterized by high energy consumption, heavy pollution and low yield. The key technology for 420mm slab casting developed by CISDI has been applied in Xinyu Steel to allow the world’s thickest slab to be produced by a vertical-curved casting machine. The casting machine in Xinyu Steel is implemented with CISDI proprietary hydraulic oscillation technology, dynamic soft reduction, automatic control of dynamic secondary cooling and spray width adjustment, etc. With continuous caster instead of mold casting to produce ultra-thick slabs, it can achieve energy savings of 1,800~2,600MJ per ton of slab, which means it can contribute to reduction in annual carbon dioxide emissions by app. 22.96 ~ 330,400 tons and reduction in per-ton steel cost by RMB210~330 if considering one 1.4 mt/a production line.