Abstract: This research has heen conducted to investigate to what extent DeST software can describe the actual influences of outdoor conditions and indoor casual gains on indoor climate, by comparing measured temperature and simulated temperature of residential buildings in Beijing. The results reveal that the same temperature changing tendency between simulated temperature and measured temperature can be achieved as long as the effects of occupancy behaviors on indoor climates are actually considered in the simulation. This demonstrates the applicability of DeST software to predicting indoor climate and assessing thermal performance of residential buildings.