This book summarizes the formation of solidification defects in continuous casting strand and the process mechanism of improving central segregation, porosity and shrinkage under solidification end reduction. The behavior rules of shell deformation, crack initiation and propagation, solute transport, shrinkage cavity closure, microstructure refinement and evolution during solidification end reduction process were systematically expounded. It introduces how to realize the accurate, efficient and stable implementation of the solidification end reduction in the production process, and the design and development of key equipment. Finally, taking the specific production lines of Baosteel and Panzhihua Iron and Steel Co., Ltd. as examples, the industrial application and effect of solidification end reduction technology are listed.