Sodium sulfate decahydrate/expanded graphite composite phase-change material(Na_2SO_4·10H_2O/EG) was prepared by vacuum adsorption method.The thermal properties of Na2 SO_4 ·10H_2O/EG,such as melting-solidification,phase separation,supercooling and latent heat were tested and analyzed.The results show that with the addition of 2%(mass fraction) borax and 8%EG,the composite phase-change materials Na_2SQ_4 · 10H_2O/EG obtain ideal properties.The phase separation is eliminated,the supercooling degree of Na_zSO...