Sustainable architecture is one of the important evolutions in the field of architecture, so that its purpose is designing based on the principles of sustainability and energy saving. In Iran, the harmony of architecture with the properties of the climate for each region, has long been considered, including the hot and dry climate. A large part of Iran is in hot and dry climate condition that has features like intense heat in summer, wind and intense cold in winter. Therefore, houses should be built in such way as to be protected from direct sunlight and intense heat and winter cold; so in this type of climate, the architecture of residential houses is introverted and important. Many buildings have survived from the Qajar dynasty in Iran, so that most of them include residential houses. The architecture of this period has been called housing architecture or residential house architecture. The purpose of this paper is to identify and express the effectiveness of the principles and elements affecting the sustainability of Qajar houses in hot and dry climate, so the factors affecting the construction of ancient sustainable houses are studied by introducing 5 examples of such these houses in Qom city and the principles, harmony and adaptation of the body of these houses with their geographical environment are recognized.