Abstract: The macroscopic characteristics of molten salts are governed by their microstructures. Research on the structures of molten salts provides the foundation for a full understanding of the physicochemical properties of molten salts as well as a deeper analysis of the microscopic electrolysis process in molten salts. Information about the microstructure of matter can be obtained with the help of several speculative and experimental procedures. In this review, the advantages and disadvantages of the various test procedures used to determine the microstructures of molten salts are compared. The typical coordination configurations of metal ions in molten salt systems are also summarized. Furthermore, the impact of temperature, anions, cations, and metal oxides (O²⁻) on the structures of molten salts is discussed in detail. The accuracy and completeness of the information on molten salt structures need to be investigated by the integration of multiple methods and interdisciplinary fields. Information on the microstructure and coordination of molten salts deepens the understanding of the elementary elements of the microstructure of matter. This paper, which is based on the review of the coordination states of metal ions in molten salts, is hoped to inspire researchers to explore the inter-relationship between the microstructure and macroscopic properties of materials.