Abstract: The thermo-physical properties of Al-34% Mg-6% Zn (in wt.%) and Al-28%Mg-14%Zn alloys used for thermal energy storage applications,such as the specific heat capacity including solid and liquid state;the mass density in the temperature range 30~500℃;the melting temperature and the latent heat of fusion were determined by differential scanning calorimetry (DSC) and H-90 type Dilatometer. The test results showed that the melting temperature and latent heat of fusion for the two alloys were 454,447℃ and 314.4,303.2kJ/kg,respectively. The density of the two alloys heated from room temperature to melting temperature were decreased by 1.05%,1.09%,respectively. The specific heat capacity of the two alloys were growing with the temperature increasing before the beginning of phase change,and were 1368.5,1203.6J/(kg·K)at 445℃,respectively. The change of specific heat capacity were great due to existing of latent heat of fusion during the phase transformation process. The mechanism of alloy compositions and phases′s effection on these properties were also discussed in this paper.