Phase change materials(PCM) can be applied in mass concrete to prevent thermal cracks. Temperature distribution was measured in center area of normal concrete and paraffin PCM concrete. Thermal conductivity of PCM mortar was measured in air dry and oven dry condition. Thermal properties of pure paraffin and PCM mortar with different paraffin content were also tested with differential scanning calorimetry(DSC). The results show that phase change concrete with paraffin can slow down both temperature increasing rate and temperature dropping rate; PCM mortar has much higher thermal conductivity than pure paraffin and slightly lower than ordinary mortar. PCM mortar has similar latent heat and phase change temperature range to those of pure paraffin.