MgCl2·6H2O is a phase change material with outstanding heat storage performance. To explore the potential of MgCl2·6H2O forming binary phase change materialsBinary phase change materials with other substances, this study focuses on five binary phase change materialsBinary phase change materials composed of magnesium chloride hexahydrateMagnesium chloride hexahydrate and various inorganic hydrated saltsInorganic hydrated salt. The eutectic point composition of these binary mixtures was calculated theoretically, and their thermal storage performance was studied experimentally. The experimental results show that a binary mixture of MgCl2·6H2O and NH4Al(SO4)2·12H2O with a mass ratio of 2.61:7.39 is suitable as a binary phase change materialBinary phase change materials. In this proportion, the phase change temperatureTemperature of the MgCl2·6H2O-NH4Al(SO4)2·12H2O binary phase change materialsBinary phase change materials is 64.3 °C, and its phase change enthalpy is 208 J/g. After 200 thermal cycles, the phase change enthalpy was found to be 182.24 J/g. This study provides new options for developing binary phase change materialsBinary phase change materials based on magnesium chloride hexahydrateMagnesium chloride hexahydrate.