Abstract: The phase change process of CH₃COONa·3H₂O（SAT）/Na₂HPO₄·12H₂O（DSP）eutectic salt was studied experimentally,and the optimization effect of hydrophilic carbon nanotubes（HCNTs）on the thermal properties of eutectic salt was analyzed.The results show that the cyclic stability of eutectic salt is best when the mass ratio of SAT/DSP is 9∶1,and the degree of supercooling is only 2.5℃.As the mass fraction of the HCNTs attained is increased,the thermal conductivity of the composite shows a linear increase trend;the highest value 1.29 W/（m·K）,which is 182.89%higher than that without HCNTs.Conversely,the heat storage density manifests a downward linear trend,reaching a maximum decrease of 5.59%.Furthermore,the cyclic stability of HCNTs/SAT/DSP composites was tested,with the results revealing that after 200 solid-liquid cycles,the cyclic stability of each group of materials is good,and it has practical application value.