The collector is an essential element of Solar Chimney Power Plant (SCPP). It converts the solar energy into heat by increase the internal energy of the air. An optimization of the collector design is required to recover further SCPP efficiency and to reduce the large plant area. In the present paper, a novel collector design with double-pass counter flow mode was proposed. For this purpose, a comparison between three models; conventional collector, double-pass collector with parallel flow and double-pass collector with counter flow was carried out using CFD methodology. The realizable k-epsilon turbulence model and the discrete ordinates (DO) non-grey radiation model were employed in the present simulations. Numerical results were validated for a reference design using test data gathered from a developed prototype built at the National School of Engineers of Sfax, in Tunisia. The distribution of the local fluid characteristics and the heat transfer modes were proven for the proposed systems. In addition, the global SCPP characteristics such as the efficiency and the driving pressure were compared. The effect of the second roof height on the system performance was analyzed for both double-passes collectors. Results show that the proposed designs are clearly affect the SCPP behavior. In fact, the double-passes counter flow collector presents an efficient solution which increases the collector efficiency by 28% comparing to the conventional collector. (c) 2019 Elsevier Ltd. All rights reserved.