Kaolinite (K) is a common clay mineral with inherent advantages such as low cost, flame retardant, and multilayer structure. In this paper, a vacuum impregnation method was used to adsorb stearic acid (SA) into dimethyl sulfoxide (DMSO) and intercalated kaolinite (IKL) pores to prepare a composite phase change material for heat storage. Thermal properties, structure and composition of the prepared composite were tested by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), thermal gravimetric(TG), differential scanning calorimety (DSC), scanning electron microscope (SEM), and Brunauer-Emmet-Tellerare (BET). The mass ratio of SA adsorbed into IKL without leakage is as high as 32.3%, ascribed to the expansion of kaolinite interlayer. The latent heat of melting and freezing is 43.36 J/g and 43.16 J/g, and the melting and freezing temperatures is 51.9 ℃ and 51.7 ℃. In addition, the composite phase change material has excellent thermal stability. Due to the high adsorption capacity, high latent heat, good thermal stability, as well as low cost, SA/IKL composite phase change material has potential application value in practical applications.