Abstract: In this paper,lauric acid（LA）and stearic acid（SA）were selected as phase change materials（PCMs）,and the binary equilibrium phase diagram of LA/SA was drawn. It is found that when the ratio of LA/SA is 7∶3,the composite PCM reaches the lowest eutectic temperature of 31.2 ℃,which is suitable for building envelope. Nano-copper oxide（nano-CuO）and nano-silicon dioxide（nanoSiO2）were added into the composite PCM as thermal conductivity enhancing materials. The effects of different dispersants,different proportions of nanoparticles and dispersants,and different concentrations of nanoparticles on the stability and uniformity of experimental materials were compared. Based on Fourier transform infrared spectroscopy test（FT-IR）,differential scanning calorimetry（DSC）,thermal conductivity measurement,and thermal absorption and release process analysis,the thermal properties were characterized and studied. The experimental results show that 0.2%nano-CuO/PCM has good stability,and the latent heat of melting and solidification decreases by 5.91% and 5.44%,respectively,and the thermal conductivity increases by 30.0% compares with that of composite PCM.