Latent heat energy storage is becoming more and more attractive for energy conservation of buildings. Phase change materials (PCMs) can be applied in building envelopes to conserve heat energy in building products. The technology of PCMs is efficient and economical due to the rising cost of fossil fuels and environmental concerns. In this paper, binary organic/inorganic nano-composite PCM by intercalation compound is prepared, preparation conditions are studied systematically; and structural analysis and characterization of performance are conducted. The results obtained show that a good potential for heating and cooling is in building through nano-composite PCM and overcomes weaknesses and deficiencies of pure PCMs. A simple modification of binary organic/inorganic nano-composite PCM is discussed firstly. Secondly, the various influencing factors of thermal storage capacity are discussed. The optimum experimental conditions for preparation of organic/inorganic nano-composite PCM are, 55%~60% for the content of organic substances, 5h for the preparation time, 70~80°C for the preparation tem. and 60~120 mesh for the best granularity of composite PCM.