The t x phase diagram and phase change temperature of hexadecanol（H） and palmitic acid（PA） with different proportions were determined by cooling curve method. The ternary system was formed by introducing lauric acid（LA） at near lowest eutectic point. With the same method the phase change temperatures and t x phase diagram of the ternary system of H/PA/LA were determined. The thermal properties and stability performance of the composite phase change material were investigated by differential scanning calorimetry（DSC） and fourier transform infrared spectroscopic（FTIR） techniques. Experimental results show that the binary eutectic mixture is formed at the different ratio of H to PA. The ternary eutectic systems can be formed by introducing LA in the binary system of H/PA when the mass ratios of H to PA are 6∶4 and 7∶3. At a mass proportion of 30∶20∶50 and 35∶15∶50（H/PA/LA）, the latent heat and the lowest eutectic point are 179.63J/g and 177.87J/g, 26.5℃ and 27.0℃, respectively. During the continuous phase change process of the ternary system no stratification was observed. The good thermal stability of the ternary system was proved by the FTIR and DSC after 1 200 thermal cycles.