Amorphous calcium carbonate (ACC) plays a very important role in the formation of calcium carbonate minerals with a multi-level hierarchical structure and excellent mechanical properties. Organisms can accurately regulate the crystallization process of ACC, while synthetic ACC is usually very unstable. Therefore, studying the stabilization mechanism of ACC and the crystallization process of ACC from a chemical perspective is of great significance for understanding the formation process of biominerals via an amorphous precursor. This article summarizes the intrinsic properties of ACC, and the influence of environmental conditions and additives on crystallization process, explains the role of ACC during the crystallization process, and discusses the implications of this field on the regulation of material structure and properties.