The effect of heat conduction intensifiers, including copper powder, carbon powder and expanded graphite, on the heat conductivity of composite phase change material(PCM) based on trihydrate sodium acetate were studied. The thermal characteristics of the PCM with or without expanded graphite added were measured by the differential scanning calorimeter. Studies have shown that expanded graphite can melt together with PCM well， and the intensified effect on the heat conductivity of PCM is obvious. When the use level(by volume) of expanded graphite is 10%, the phase transition enthalpy of PCM is 307.762kJ/kg, this is 2% less than that without expanded graphite added, but the thermal conductivity increases 2 times.