Phase change energy storage mortar helps to stabilize the temperature of the indoor environment, which is of great significance to the realization of building energy conservation. A study has been made of the relationship between the content of phase change micro-capsules and the fluidity, apparent density, flexural strength and compressive strength of the mortar. The results show that with the increase of phase change micro-capsule dosage, the fluidity of the mortar decreases, and the apparent density, flexural strength and compressive strength all undergo an initial increase and a subsequent decrease. The optimum mass fraction of the phase change micro-capsule to replace the quartz sand is 10%, at which point, the compressive strength of the mortar increases by 37.1%, compared with that of the mortar without the phase change micro-capsule.