Taking phase change energy storage mortar board with capric acid microcapsule as the research object, the temperature control effect of phase change energy storage mortar board with capric acid microcapsule in building envelope was verified by experimental test and numerical simulation. The results show that compared with phase change energy storage mortar board without capric acid microcapsules, the thermal conductivity of that decreases by 8% and 21% respectively, but the thermal storage coefficient increases by 3% and 11% respectively when the content of capric acid microcapsules are 2% and 4%. In the numerical simulation and experimental verification, the plane temperature of mortar board shows a gradient distribution, and the difference of overall temperature in the plane is not large. Compared with phase change energy storage mortar board without capric acid microcapsule, the phase change completion time of that with 4% capric acid microcapsules was delayed by 20min, the temperature of that with capric acid microcapsules was significantly delayed, phase change energy storage mortar board with capric acid microcapsules have a good temperature controlling effect. The more the capric acid microcapsules in phase change energy storage mortar board, the better the temperature controlling effect.