Numerical simulations have been performed to analyze the characteristics of heat transfer and air flow in the solar chimney power plant system with an energy storage layer. Different mathematical models for the collector, the chimney and the energy storage layer have been established, and the effect of solar radiation on the heat storage characteristic of the energy storage layer has been analyzed. The numerical simulation results show that: (1) the heat storage ratio of the energy storage layer decreases firstly and then increases with the solar radiation increasing from 200 W/m(2) to 800 W/m(2): (2) the relative static pressure decreases while the velocity increases significantly inside the system with the increase of solar radiation; (3) the average temperature of the chimney outlet and the energy storage layer may increase significantly with the increase of solar radiation. In addition, the temperature gradient of the storage medium may increase, which results in an increase of energy loss from the bottom of the energy storage layer. (C) 2008 Elsevier Ltd. All rights reserved.