Two kinds of stearic acid (SA)/ attapulgite (ATTP) composite phase change materials (PCMs) were prepared for the latent heat thermal energy storage (LHTES) in buildings or other area by the methods of fusion and immersion, using SA as PCMs and ATTP supplied by Linze of Gansu province as supporting material. The structure, thermal properties, thermal reliability and heat storage or release performance of the composite PCMs were determined by scanning electron microscope (SEM), fourier transformation infrared (FTIR), differential scanning calorimetry (DSC) and thermal cycling test analysis technique. The results indicate that the preparation method has no effect on the structure and morphologies of the composites. Two kinds of composites have same structure due to the SA adsorbed in the surface of ATTP by physical reaction. The results also show that two form-stable composites PCMs have the optimal effect for preventing SA leak from the composite emerges when the maximum load proportion of SA in the composites were 38.64wt% and 29.13wt%. The latent heats and phase change temperature were measured as 68.71 J/g and 57.3℃ for the composite which was prepared by fusion method and 51.79 J/g and 55.2℃ for the composite fabricated by immersion method, respectively. The results of DSC, FTIR and thermal cycling test are all showing that two kinds of composites have good heat storage property but the composite prepared by fusion method has a better thermal and chemical stability.