The Korean small modular reactor, SMART (System-integrated Modular Advanced ReacTor), is designed to achieve enhanced safety and improved economics through reliable passive safety systems, a system simplification and component modularization. SMART can be used for multi-purpose such as electricity generation and seawater desalination. However, due to the multi-purpose characteristics of SMART, the net electricity generation is decreased compared to the reactor for electricity generation purpose only. A supercritical CO2 (S-CO2) Brayton cycle, which is recently receiving a significant attention as the next generation power conversion system, has some benefits such as high cycle efficiency, simple configuration, compactness and so on. In this study, the authors evaluated the applicability of SMART based co-generation plant producing electric power and desalination process with the S-CO2 Brayton cycle to minimize the decrease in the total electricity production capacity due to the desalination process.