Abstract: In order to enhance specific heat capacity of the low melting point salt (Ca(NO ₃) ₂-KNO ₃-NaNO ₃-LiNO ₃), low melting point salt(LMPS) nanofluid was prepared by adding SiO ₂ nanoparticles with size of 20nm into the low melting point salt with using ultra-sonication. The influence of nanoparticles dispersion on enhancing specific heat of the low melting point salt was investigated by experiments. Two factors of ultra-sonication (time for sonication and frequency) were researched. The specific heat capacity was measured by using a differential scanning Calorimetry (DSC), and the microstructures following solidification was observed by using a scanning electron microscope (SEM). Results show that the specific heat of the LMPS nanofluid is significantly improved, when nanoparticles disperse evenly in the LMPS nanofluid. The average specific heat of the LMPS nanofluid is 1.868J/(g·K) and the enhancement of the specific heat is 14%~22% in 200~350℃. Moreover, it is verified the fact that the ultra-sonication is a stable method of preparing LMPS nanofluid.