Phase change material (PCM) integrated with building envelopes could enhance thermal storage performance of building envelopes significantly. Due to the variable physical property of PCM, the thermal performance of PCM envelopes is different from traditional envelopes such as clay brick and concrete wall. In the present paper, the thermal performance of PCM envelopes are experimentally investigated in an artificial climate chamber. The experimental PCM wallboard is made by PCM layer, concrete layer and insulation layer, which could reflect the real envelopes structure in typical office buildings in Western China. The thermal performance of the wallboard with different material layer locations is compared, and the thickness of PCM layer is optimized. During the experiments, the PCM wallboard is under double-sides heat effect, including periodic outdoor air temperature fluctuation and indoor heat source. Two indicators named thermal inertia index and coefficient of heat accumulation of interior surface are introduced as the key parameters to evaluate the thermal storage performance of the PCM envelopes. The results show that, under double-sides periodic thermal effect, the indoor air temperature is mainly affected by the coefficient of heat accumulation of interior surface of the PCM wallboard. However, the increment of the thermal inertia index of the whole wallboard has little influence on the indoor thermal environment under double-sides periodic thermal effect.