A kind of new energy efficiency building system-LHTES (latent heat thermal energy storage) system combined with nigh ventilation is proposed. Its advantages, operating , a kind of LHTES system design built in the space between a hung ceiling and the floor above it applied in a typical residence is described. The performance of cool charging and discharging is simulated and its economics analysis is undergone. The results show that this system can improve indoor thermal comfort level during summer and intermediate seasons for the rooms without air-conditioning systems or can save much energy for the rooms with air-conditionings system.