A kind of innovative building energy efficiency system-Night Ventilation with PCM Packed Bed Storage (NVP) system is proposed. The mathematical model of NVP system is built to analyze its thermal behavior. The building thermal inertia, the model of Latent Heat Thermal Energy Storage (LHTES) system and the ventilation scheme are all taken into considered in the mathematical model. An experimental installation of NVP system used in Beijing is introduced. Its thermal performances including the effect on decreasing the room temperature and the energy consumption are discussed. Experimental results show that NVP system has great potential in the field of energy efficiency building. And the mathematical model of NVP system is validated with the experimental data.