The realization of kilowatt-level transparent laser ceramics has brought innovation to existing crystal and glass-based laser applications, laying the foundation for advanced projects such as nuclear fusion and space solar collection in the future and contributing to the development of China’s “rare earth economy.” Combining with engineering cases, this book systematically introduces the structure, properties, preparation, applications, and development of this type of emerging materials from the perspective of optical function material research. This includes historical origins, the influence of unique polycrystalline structures, improvements required for ceramic structures and processes to transition from traditional opaque to transparent laser applications and the theoretical mechanisms, virtual design and simulation for materials lasers, and prospects for future technological and material development.