Abstract: In the report， the effects of density， temperature and moisture content on thermal conductivity of aerated concrete block was analyzed and the sorption isotherm was established. Based on the climate characteristic of Hainan Island with high temperature and high humidity， Design Builder software was used to simulate the effect of thermal conductivity on building energy consumption in the typical village of Hainan Island under this climate condition. The results showed that in conventional building energy-saving design， the thermal conductivity of materials in the adiabatic state and at 20 ℃ to calculate building energy consumption can lower the results， the variation of building cooling energy consumption was consistent with that of thermal conductivity.