Inorganic hydrated salt, as a kind of important phase change materials (PCMs), possess the characteristic of high latent heat of phase change, easy availability and high safety, has a great potential in the application of middle-low temperature thermal energy storage in the future. However, the inherent supercooling and phase separation of the inorganic hydrated salt decreased the thermal stability of these materials, and these problems always resolved by adding nucleating agents and thickening agents. The leakage problems of hydrate salt in liquid state always resolved by the absorption and the microencapsulation method, to limit them in a certain area. So far, by means of porous matrix adsorption, such as expanded graphite, bentonite, foam metal, inorganic hydrated salt PCMs can be absorbed in these matrix and well packaged to prevent them from leakage. Through the microencapsulation method, inorganic hydrate salt can be encapsulated in the organic or inorganic polymer shells such as polymethyl methacrylate, melamine-formaldehyde resin or the polyurethane, inorganic SiO2 shell is another choice for the encapsulation of the materials. Through the absorption or micro-encapsulation method, the dispersibility of the inorganic hydrate salt can be further improved, the supercooling degree of the inorganic hydrate salt can be reduced and the phase separation can be modified, the thermal stability of the materials can be further enhanced, which is an effective way to conquer the leakage problems of the inorganic hydrate salt in the phase change process. In this work, the study on the supercooling and phase separation of inorganic hydrated salt were summarized, for the inhibition of the supercooling and phase separation of inorganic hydrated salt, some methods including absorption of porous materials or microencapsulation method were proposed. Finally, suggestions for future research on energy storage using inorganic hydrated salts were provided.