Nowadays energy and electricity production is one of the major concern of governments. Electricity generation by solar systems is considered as one of the alternative for fossil fuels. There is a surge in the use of the solar chimney power plant in the recent years which accomplishes the task of converting solar energy into kinetic energy. In this study a numerical simulation and geometrical parameters optimization of the solar chimney is discussed. In this paper, solar chimney prototype in Manzanares, Spain, as a practical example is used. To explore the geometric modifications on the system performance (output power and efficiency), effect of chimney height, collector radius and collector height is studied. A numerical simulation in this paper were used to evaluate the performance of a solar chimney power plant system, in which the effects of various parameters on the relative static pressure, driving force, power output and efficiency have been further investigated. In order to validate the present work, upwind velocity in the solar chimney was compared with an experimental model.