Natural ventilation is a prevailing way to relieve the indoor thermal environment against warmand humid climate. The field measurement of the thermal performance of a model house withnaturally ventilated double skin walls compared with a conventional insulated model housewas carried out. Only the gap between the double skins is ventilated, while the indoor of theconventional model is ventilated mechanically. The measurement results show that the insidesurface temperature, the room air temperature and the indoor relative humidity of the doubleskin wall house are lower than those of the conventional model house all the year round. Thenatural ventilation between the double skins can keep the indoor space cooler and drier thanmechanical ventilation in the conventional model. This type of outside wall is recognized to beeffective against warm and humid climate.