Phase change material (PCM) used in buildings can increase building energy efficiency and decrease indoor temperature fluctuation. In this study, composite PCM was composed of paraffin and expanded perlite (EP) (60 wt%, 40 wt%) and was prepared through a self-made vacuum absorption roller. A phase change material wallboard (PCMW) was fabricated by the prepared composite PCM through the mould forming method. A plate type heat accumulator (HAR) with embedded copper tubes was connected to a solar thermal heating system. HAR is fully filled with paraffin, which can store or release the heat gained by the solar thermal heating system. Therefore, PCM active and passive combination is realised through the PCMW incorporated in the building wall and the HAR connected to the solar thermal heating system in the same building. In order to analyze the performance of PCM active and passive combination, two same cubes were used to conduct a contrastive experimental study using different strategies under the winter conditions. The experimental result has indicated that (1) PCMW with melting point of 24.88 degrees C and latent heat of 59.68 J/g was incorporated in the walls, passively enhancing the thermal inertia of building envelope; (2) HAR with PCM extended the service period of solar thermal heating system; (3) PCM active and passive combination further enhanced the thermal performance of building envelope, indoor thermal comfort and building energy efficiency.