This paper investigates the effect of amount of Paraffin-encapsulated phase change material (PCM) on the thermal energy storage of cement mortar for developing energy saving concrete. The PCM with melting point of 44℃ was used in this study. The added amounts of PCM in the cement mortar were 0, 10, 20 and 30% of cement weight. The results indicated that the heat storage properties of cement mortar was improved with increasing contents of PCM.