The thermal performance of a cavity receiver in the solar tower power plant crucially relies on the spatial relationship of its polyhedral geometric inner surfaces. So far, it has always been a focus to propose a model coupling the convection and radiation heat transfer for a large-size receiver. Based on the net energy exchange and thermal equilibrium principle, a radiation heat transfer model in terms of the angle factor equations of inner surfaces in the receiver was developed in this work. The finite difference method with an automatic mesh generation technique was employed to disperse the angle factor equations of inner surfaces in the receiver. Consequently, the thermal performance of the cavity receiver was evaluated while convection heat transfer between the receiver inner surfaces and ambient air was to consider with the available convection correlation. The results showed that the thermal efficiency of the cavity receiver increased with the increase of incident heat flux. When the width-depth ratio decreased, the cavity efficiency increased first and then decreased. With regard to different receiver structure parameters, the total heat loss of the receiver varied differently with the increase of the heat absorption area to the aperture area ratio. Meanwhile, the design of the cavity receiver structure in the MW solar power tower plant in Yanqing, Beijing was optimized according to the model proposed. (C) 2017 Published by Elsevier Ltd.