This study focuses on the preparation and thermal properties of paraffin/expanded perlite composite as novel form-stable phase change material for latent heat thermal energy storage by vacuum impregnation method. The paraffin could be absorbed in pores of expanded perlite as much as 55 wt% without melted phase change material seepage from the composite and this mixture was described as form-stable composite phase change material. The melting and freezing temperatures and latent heats of form-stable composite phase change material were measured using differential scanning calorimetry analysis. The thermal cycling test indicated that the form-stable composite phase change material had good thermal reliability in terms of the changes in thermal properties after 5,000 thermal cycling. Thermal conductivity of the form-stable composite phase change material was increased by about 46% by adding 5 wt% expanded graphite. The results indicated that the prepared form-stable paraffin/expanded perlite/expanded graphite composite phase change material has a great potential for latent heat thermal energy storage systems solar passive heating purposes due to suitable phase change temperature, high latent heat capacity, good thermal reliability, and thermal conductivity.