Abstract: In order to make full use of solar radiant heat in winter,traditional building materials and phase change materials are combined to form a new type of green building material,which can give full play to the performance of energy storage and temperature control,shorten the time for heat to be absorbed into the room,reduce energy consumption in winter heating and realize building energy conservation.Capric acid-paraffin（CA-PC） binary low-eutectic composite phase change materials were prepared by melting blending method,and the optimal mass ratio of CA-PC binary composite phase change material was determined by step cooling curve method to be 0.81:0.19,and the eutectic temperature was 27.4 ℃.It was found that CA and PC were combined by physical action by Fourier infrared spectrometer（FT-IR）.And 500 times of accelerated melting-freezing cycling showed that the CA-PC composite phase change material had good thermal cycle stability.In addition,the differential scanning calorimeter（DSC） analysis showed that the phase change temperature of CA-PC was 27.0 ℃ and the latent heat of phase change was 153.7 J/g,which is consistent with the eutectic temperature obtained by the step cooling curve.It is further indicated that the composite phase change material has great development potential in the field of preparation of new building energy storage materials.