In order to ensure healthy and comfortable indoor environment it has to be proper ventilated either by mechanical devices or in a natural way that is more energy efficient. Natural ventilation is achieved as a result of pressure and/or temperature difference. In this paper the solar chimney, which is used for improving room natural ventilation creating the temperature difference by heating the air by the sun, is analytically and numerically studied. In this study an optimization of the composition and the thickness of the absorber wall is made to enhance the air flow rate through solar chimney. The result have been compared with previous study on solar chimney.