Twist-bend nematic phase is a chiral nematic phase with an inclined spiral structure possessing nanometer helical pitch. Due to its negative bend elastic constant, nano-scale pitch, and chiral structure formed by achiral molecules, it has attracted widespread attention from researchers all over the world. This article reviews the development of twist-bend nematics, focuses on the study of the characteristics, properties, molecular motion, and molecular groups of twist-bend nematics, and illustrates the effects of twist-bend nematics under external fields. The microstructure changes and the development of theoretical and simulation research on twist-bend nematic phase, and the application prospects and development trends of twist-bend nematic liquid crystal are discussed. The aim of this article is to provide readers with a comprehensive understanding of the related research of the special liquid crystal optical materials through the review of the materials characteristics, properties, applications and other aspects of twist-bend nematic liquid crystals, and thus stimulate the readers research inspiration on their phase structure, theoretical simulation, applications, etc. It is hoped that this paper can start a discussion and promote the research and development of this field to some extent.