Repowering as a formerly-experienced method can be considered as a suitable solution in raising the quantity and quality of generated electricity. The full repowering can provide appropriate solutions for converting the status of existing steam power plants (SPP) to assemblies with acceptable generation quality and reach current world standard levels. In this study, due to the importance of Bandar Abbas steam power plant, in terms of positioning and the amount of generated electricity, full repowering is considered. After modeling and verifying the model, the results of modeling the desired states in performing repowering are presented. Optimization is performed using functions of exergy efficiency and cost of electricity generation, using genetic algorithm method. Finally, the obtained diagram (Pareto Curve) indicates the cost changes based on the exergy efficiency that are effective in deciding on and selecting the desired and appropriate investment state. The results of the multi-objective optimization of repowering with two single-pressure and double-pressure level Heat Recovery Steam Generators (HRSGs) indicate an increase in the exergy efficiency of the plant up to a level above 46%. (C) 2018 Elsevier Ltd. Ail rights reserved.